Dark Waters: Water Contaminants in the Movies

civilaction

 

A highly promoted movie called Dark Waters came out in late November 2019. It stars Mark Ruffalo and tells the story of Cincinnati lawyer Rob Bilott and his dozen-year battle against the centuries-old American chemical company, DuPont.  From an effort to gain justice for a single client whose livestock were poisoned by Dupont’s chemical PFOA, Bilott’s efforts resulted in large class-action settlements for hundreds of injured parties. Ruffalo, who is known as an environmental activist as well as an actor, produced the film as well as starring in it. Other top actors featured are Anne Hathaway and Tim Robbins.

Dark Waters joins other important movies that brought significant water contaminants to public attention. The stories of all are similar. They feature an individual who takes on a powerful company that seems to be above the law.  The best known of these is Erin Brockovich, starring Julia Roberts, which tells the story of the hexavalent chromium (aka chromium-6) poisoning of the water in Hinkley, CA by Pacific Gas and Electric. A lesser known but equally compelling story is that of the TCE poisoning of the wells that supplied Woburn, MA by the W.R. Grace company. The incident inspired an outstanding book by Jonathan Harr that in turn inspired the 1998 movie A Civil Action, starring John Travolta and Robert Duvall. (The book was better than the movie, but both deserve your attention.)

Why Don’t Tiny EOT (End of Tap) Filters Don’t Work Well As Standard Filters? Well, Because They Are Tiny

Most of the bad publicity (“filters don’t work”) that resulted from poor performance on tests done on lead filters supplied to homeowners in Flint and Newark ignored the fact that the filters provided were novelty-sized units meant for off-the-shelf purchase. They could not be expected to “work” as well as full-sized filters actually designed for long-term  use in homes.

Here is sizing information from the manufacturer of MetSorb®, a heavy metal removal medium that is added to carbon block filters to give them lead-removal capacity.

 


A nominal 10 – inch carbon block, standard for most countertop and undercounter applications, will provide more overall volume and more functional media than the 2 to 2-1/2 inch blocks typically used in end-of-tap (EOT) applications. For example, a nominal 10 – inch carbon block can easily perform for 1000 gallons or more of contaminant reduction, while the smaller EOT blocks are rated at several hundred gallons.

The larger block design also gives longer contact times (EBCT or Empty Bed Contact Time) for better contaminant reduction. For example, a nominal 10 – inch block will provide an EBCT of 10 -15 seconds, while a typical 21/2 inch EOT block gives only 3 seconds EBCT. Devices designed for slower flow rates, e.g., 0.5 gpm (gallons per minute) versus 1.0 gpm will provide longer contact times and better percentage contaminant reduction.

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This 10″ carbon block fits standard sized countertop and undersink filters and provides 2500 gallons of lead-free water at 0.75 gallons per minute.   

President Trump Addresses Water Conservation

At a December 16, 2019 meeting of small business leaders at the White House, President Donald Trump talked at length about water and energy conservation, saying the Environmental Protection Agency is looking into restrictions in part because people are flushing their toilets 10 to 15 times instead of once and are therefore using more water.

“We have a situation where we’re looking very strongly at sinks and showers and other elements of bathrooms, where you turn the faucet on in areas where there’s tremendous amounts of water, where it all flows out to sea because you could never handle it all, and you don’t get any water,” he said.

“They take a shower and water comes dripping out, very quietly dripping out. People are flushing toilets 10 times, 15 times, as opposed to once; they end up using more water. So EPA is looking very strongly at that, at my suggestion.

“You go into a new building, new house, a new home, and they have standards where [you] don’t get water, and you can’t wash your hands practically; there’s so little water,” he added. “And the end result is that you leave the faucet on, and it takes you much longer to wash your hands, and you end up using the same amount of water. So we’re looking very seriously at opening up the standard, and there may be some areas where we go the other route, desert areas, but for the most part, you have states where they have so much water where it comes down — it’s called rain — that they don’t know what to do with it.”

In his comments, the president appeared to be referring to the standards set by the National Energy Policy Act of 1995, federal regulations that stipulated that all newly manufactured toilets had to use a maximum of 1.6 gallons of water per flush, a significant decrease from previous standards.

Just a couple of days earlier, at a NATO conference in Europe, the president blamed ocean trash in US waters on the bad habits of other countries:  “I also see what’s happening with our oceans, where certain countries are dumping unlimited loads of things in it. They float — they tend to float toward the United States. I see that happening, and nobody has ever seen anything like it, and it’s gotten worse.”‘

Sulfur & Groundwater

 

Gazette’s Introductory Note: The piece below is adapted from an information sheet provided by the non-profit Water Systems Council.  It addresses one of the more confusing topics in water treatment, the “sulfur” or rotten egg smell in well water. Bad smelling water is variously attributed to sulfur, sulfate, or hydrogen sulfide. This document seeks to shed some light on the origin and treatment of bad smelling water. 

womanholdingnose2

What is Sulfur?

Two forms of sulfur are commonly found in drinking water: hydrogen sulfide and sulfate-reducing bacteria. Both forms are nuisances that usually do not pose a health risk at the concentrations found in domestic wells.

Hydrogen sulfide gas occurs naturally in some ground water that contains decaying organic matter, such as wetlands, marshes, swamps, river beds. It may be found in deep or shallow wells. Hydrogen sulfide is often present in wells drilled in shale or sandstone, or near coal or peat deposits or oil fields.

Sulfate is a combination of sulfur and oxygen, and is part of naturally occurring minerals in some soil and rock. The mineral dissolves over time and is released into ground water. Sulfur odor is produced when a non-harmful sulfur-reducing bacteria digests a small amount of the sulfate mineral.

 

What are the health effects of Sulfur?

 

The EPA considers sulfur a secondary water contaminant, with no direct threat to human health. Sulfate gives water a bitter taste and can have a laxative effect that may lead to dehydration. Hydrogen sulfide gives water a “rotten egg” odor and taste, and can cause nausea.

 

Hydrogen sulfide is corrosive to metals such as iron, steel, copper and brass. It can tarnish silverware and discolor copper and brass utensils. Hydrogen sulfide can also cause yellow or black stains on kitchen and bathroom fixtures. Coffee, tea and other beverages made with water containing hydrogen sulfide may be discolored and the appearance and taste of cooked foods can be affected. High concentrations of dissolved hydrogen sulfide also can foul the resin bed of an ion exchange water softener.

 

How do I test for Sulfur?

 

Testing for hydrogen sulfide can be difficult because the gas escapes into the atmosphere so quickly. Onsite testing is the most accurate method for determining hydrogen sulfide concentration, especially if the odor is excessive. Hydrogen sulfide concentrations greater than 5 mg/L are more difficult to treat and could require special testing methods to assure accuracy.

 

Sulfate-reducing bacteria is rarely tested, however testing for sulfate ion (mineral) concentration is. The premise is: if a rotten egg odor is present and the sulfate ion concentration is excessive – greater than 150 mg/L – the odor is created by sulfate-reducing bacteria.

 

The EPA sets standards for secondary water contaminants based on taste, odor, color, corrosiveness, foaming and staining properties. Hydrogen sulfide is not regulated because any concentration high enough to pose a health hazard will also make the water too unpalatable to drink. The EPA’s secondary limit for sulfate in drinking water is 250 parts per million (ppm).

 

What are the treatments for Sulfur in drinking water?

 

Treatment options depend on the form (whether hydrogen sulfide or sulfate-reducing bacteria) and quantities of the “rotten egg odor-producing” contaminants. Hydrogen sulfide treatment is with chlorination or aeration followed by filtration. Often, treatment for hydrogen sulfide is the same as for iron and manganese, allowing the removal of all three contaminants in one process.

 

Most water heater anode rods contain some sulfate so, in the presence of sulfate-reducing bacteria, a rotten egg odor is created in the hot water only. If this occurs, the first course of action is to replace the anode rod with an aluminum-based rod which limits the sulfate and therefore stops the odor.

 

Sulfate-reducing bacteria is treated with continuous chlorination. Removing sulfate mineral is difficult and usually not feasible, so chlorination kills the bacteria instead. The chlorination process involves a chemical feed pump system that injects a chlorine solution into the inlet of a retention tank that must be installed in the house piping. The retention tank must hold enough water to provide a 20-minute time period for the chlorine to react with the bacteria. The capacity needed for the retention tank can be calculated by multiplying the well pump output times 20. A continuous chlorine residual of 1.0 mg/L is required at the outlet of the retention tank to assure the bacteria were destroyed. Since chlorine can be combined with natural organic matter, it’s always recommended that an activated carbon filter be installed after the retention tank to remove the chlorine.

 

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Easy Test for ORP


Posted November 30th, 2019

 

 Testing for ORP with Potassium Permanganate

Editor’s Note: The instructions below, which we’ve modified a bit, were prepared by the original manufacturer of Filox-R iron removal media. The purpose is to provide a quick and easy way to determine if your water can be treated by standard manganese dioxide-based iron filter media like Filox without the use of additional oxidizers like chlorine, air, ozone, hydrogen peroxide or potassium permanganate. 

 

Oxidation Reduction Potential (ORP) can be the most important factor to take into consideration in certain waters. Highly reducing waters may cause premature exhaustion or even destruction of the Filox-R bed.

 

Precautions can be taken prior to installation that can prevent ORP problems. Use one of the screening tests and follow the instructions below if the subject water has reducing properties that will require additional oxidants. 

 

 The Simple Test

 

Mix 1.75 ounces (50 grams) water with 0.75 ounces (22 grams) of potassium permanganate crystals. Then take 2 drops of the mixture and stir into a fresh ¼ gallon (1 liter) sample of the subject water. Let the subject water stand for 15 minutes. If the pink color remains, Filox-R can be installed without additional oxidants. If the pink color disappears, additional oxidants will be needed for Filox-R to function properly.

 

The ORP Test with a Meter

 

Note: Must use a calibrated ORP meter. Any reading that is above a negative 170 millivolts indicates that Filox-R can be used effectively without additional oxidants. Any reading falling below a negative 170 millivolts indicates that additional oxidants will be required.

 

The amount of oxidant required for proper installation can be determined by measuring the amount of oxidant added to a specific volume of subject water until the solution remains pink or the meter reads at negative 170 millivolts or above. An extrapolation can then be made to determine the correct feed rate for the oxidant with respect to the subject water flow rate. Once installed, sample the solution after the injector and mixer and repeat the above test to confirm that the feed rate is correct.

 

How to Pick the Best Filter Cartridge

The “best” water filter cartridge is not necessarily the one that removes most contaminants or the one that treats the most gallons of water or the one that has the least pressure drop. The best for you is the one that does what is needed in your application.

This article makes some generalizations about water filter cartridges to help clarify what performance information provided by manufacturers means to the filter customer. We’re using “whole house” carbon filter cartridges, 4.5″ X 20″, treating chlorine and chloramine, to illustrate, but the principles apply as well to other filters, like sediment filters and “media” cartridges that are intended for problems like iron, turbidity, lead,  and nitrate reduction.

In general terms, the more tightly the filter media is packed together, the more effective the filter is at removing contaminants, but the more it restricts the flow of water through it and the more likely it is to become clogged by particles. The looser the media is packed, the less effective the filter is at contaminant removal, but the less it restricts the flow of water and the less likely it is to be clogged. Tighter means more effective performance but greater pressure loss.

Another generalization that’s true of most cartridges is that the slower the water goes through the filter, the more effectively it treats contaminants, the longer it lasts, and the less water pressure is lost. Conversely, the faster the flow, the poorer the performance, the greater the pressure loss, and the shorter the lifespan of the filter.

The art of selecting a filter, then, is to choose one that’s tight enough to be effective but not so tight that it restricts service flow or stops up easily. It must also be large enough to accommodate the needed service flow rate. Sometimes with cartridge filters to get a larger filter the most practical approach is to install 2 or more filters in parallel.  (See the picture below.)

To see how pressure drop, capacity, and micron size are related, here is a comparison of chlorine treatment figures for  two 4.5″ X 20″ MatriKX carbon blocks, identical except in tightness. (Micron size is the way filter makers state tightness: the lower the micron number, the tighter the filter.)

Two Identical Carbon Block Filters of Different Micron Ratings: Chlorine Reduction

MatriKX CTO MatriKX CTO+
Filter Type Coconut Shell Carbon Block Coconut Shell Carbon Block
Micron Rating Nominal 5 microns Nominal 1 micron
Chlorine Removal Capacity 34,000 gallons @ 7 gpm 160,000 gallons @ 7 gpm
Pressure Drop 8 psi @ 7 gpm 16 psi @ 7 gpm
Current Retail Price $68.00 $89.00

Considerations

The very tight CTO+ would seem like the better value in terms of gallons treated per cost, but it is very unlikely that in residential use such a tight filter would treat 160,000 before it stops up. Also, the excessive pressure drop gets even worse as the filter picks up particulate. Its performance is remarkable, but it probably is not the better choice for whole house residential treatment of chlorine.

The looser CTO has half the pressure drop. Most residential water use is at a rate below 7 gpm, so you can expect the 34K capacity of the CTO to go up. We’ve found the CTO to be an excellent residential filter for water treated with chlorine.

The pair of filters compared below are identical “radial flow” granular filters. Though both are rated at 25 microns, the chloramine filter evidently uses a finer carbon and is therefore a bit more restrictive.  These are very high grade radial flow cartridges, not to be confused with the standard axial flow cartridges that normally use regular-grind (not powdered) carbon and have much lower performance numbers.  (Axial vs. radial explained.)

Similar Radial Flow Granular Carbon Filters: One for Chlorine, the other for Chloramine

Pentek RFC20BB—Chlorine Grade Pentek CRFC20BB –Chloramine Grade
Filter Type Radial Flow GAC (powdered) Radial Flow Catalytic GAC (powdered)
Micron Rating 25 Microns 25 Microns
Chlorine Removal Capacity 70,000 gallons @ 4 gpm Unknown
Chloramine Removal Capacity Unknown

10,000 gallons @ 5 gpm

25,000 gallons @ 2.5 gpm

Pressure Drop

0.9 psi @ 4 gpm

2 psi@ 7 gpm

4 psi @ 11 gpm

1 psi @ 2.5 gpm

2.5 psi @ 5 gpm

5 psi @ 7 gpm

Current Retail Price $95.00 $168.00

Considerations

Reducing the flow rate more than doubles the lifespan of the chloramine cartridge. While this ratio doesn’t apply everywhere, as a general rule cutting the flow rate through the filter significantly adds to its life expectancy, adds to its efficiency, and reduces pressure drop. Therefore, running two filters in parallel more than doubles the valve of a single filter. In many cases using multiple filters actually costs less than using one, plus you get lower pressure drop.

doublecarbonfilter02

 Split installation: each filter gets half the flow rate. Efficiency goes up, pressure drop goes down, and cost goes down.

With a flow rate of 5 gpm, one filter treats 10,000 gallons with a pressure drop of 2.5 psi, but two filters treat 50,000 gallons with a pressure drop of 1 psi. What’s more, operation cost is 1.6 cents per gallon for one filter and 0.66 cents for two.

Flow rate matters!

Ultrafiltration Problems


Posted November 12th, 2019

Common Problems Of Ultrafiltration System Operations

By Nick Nicholas

Gazette Introductory Note: This article is being reprinted because it presents a concise, easy-to-understand explanation of the ultrafiltration process. It concerns use of UF for wastewater treatment, but the problems it raises–membrane fouling and scaling, waste stream disposal, etc.–apply as well to residential applications. We (Pure Water Products) do not currently offer residential ultrafiltration units for the whole home partly because the issues detailed in the article should be addressed by professionals rather than home owners, our main customers. –Gene Franks.

One facet of technological advancement is attempting to mitigate the more glaring issues that consistently crop up due to the nature of a system process. Of course, even with decades of improvement nothing is infallible. In this article, we will discuss the common issues that can occur using UF filtration systems.

Ultrafiltration is a pressure driven membrane separation technology that is a compact and refined filtration method utilized in drinking water and tertiary wastewater reuse applications. Its semipermeable membrane can remove solids as small as 0.01 microns, including silt and viruses. However, membrane filtration technologies will have problems without proper care for appropriate pretreatment, operation, and maintenance.

UF filter systems are typically affected by three main issues:

Membrane Fouling

UF filtration, like any other membrane separation technology including reverse osmosis, is susceptible to what is known as membrane fouling. In simple terms, fouling is what happens when particulate matter adheres to the surface of a membrane. The unchecked buildup will eventually cause reduced efficiency, a pressure drop, and increased energy consumption.

There are a few different types of fouling that can occur. Each has its own cause as well as some differences in effects. Of these membrane foulants, some are reversible and others are irreversible.

Solids

Suspended solids and colloidal particles collect on the surface of the ultrafiltration membrane as well as within its pores, preventing the flow of water through the membrane. This fouling occurs more commonly in applications with high turbidity and suspended solids without appropriate pretreatment.

Scaling

Membrane scaling is not unlike what happens in pipes that carry water with high concentrations of hardness materials. When the concentration of these dissolved minerals is high enough to surpass the saturation limit of the solvent solution, they begin to precipitate out of solution onto the surface of the membrane. These minerals can crystalize, which makes them nearly impossible to remove without some sort of chemical cleaning or antiscalant pretreatment. Calcium and magnesium are two primary minerals that can cause scaling to occur on the UF filter system’s membranes.

Microbiological

Biological contaminants like algae and microorganisms are often found in surface water sources. Provided with a warm environment and low flow rates, these contaminants will attach themselves to the surface of a membrane and begin multiplying. Over time, they can form a film that will prevent water from passing through the membrane and cause an increase in the trans membrane pressure differential. This increased pressure differential will put more strain on the pumps and increase the amount of energy they draw.

Waste Stream Disposal

This relates to the UF filter concentrate discharge. The filtration system did what it’s supposed to do and you have clean water that you can safely discharge into an outdoor stream without having to pay any environmental regulation fines. Or maybe you are going to reuse it somehow. Regardless of what is going to happen to it, you have this water resource.

However, what about all that contaminants that were removed? Sadly, this concentrate stream didn’t disappear into thin air, never to be dealt with again. Nope. It’s still there, whether it’s stuck to the membrane or sitting in a concentrate waste tank, and something needs to be done about it.

The problem is, you can’t just toss it out the window and call it a day. This reject wastewater is a concentrated form of whatever was in the feedwater. Therefore, in some cases, it may be safe enough to discharge into the environment; however, in others, the facility would be charged a hefty fine if it contains harmful pollutants.

Increased Permeate Contamination

This point is pretty rare for systems that are well maintained and monitored. To reiterate, permeate refers to the water that has been separated from the contaminating solids. It’s the clean water that you get out of this filtration process. Therefore, it’s definitely an issue when you start noticing that the quality of your permeate water is getting worse. Either there are larger solids or bacteria that should have been retained by the membrane contaminating the water.

This decrease in removal efficiency is usually indicative of a compromised membrane. Polymeric membranes can get worn out over time. High temperature or pH levels can degrade them pretty quickly, and without a decent pretreatment regime, rough particles can damage the inner pores of the membrane. To state the obvious, membranes do not work very well if they are full of additional holes (other than their pores of course). And now the system isn’t meeting it’s designed specifications and you have to replace the membrane and recirculate the contaminated permeate.

Source: Water Online.

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1,4-Dioxane


Posted November 10th, 2019

 

Residential Water Treatment for 1,4-Dioxane

by Gene Franks

dioxaneskull02

 

As with many contaminants, most of the research done on 1,4-dioxane treatment is focused on large applications like wastewater treatment plants and municipal water suppliers.  Often, methods that prove effective for large operations are impossible to apply to residential treatment. In the case of dioxane, advanced oxidation processes involving hydrogen peroxide with ultraviolet (UV) light or ozone and anion exchange with specialty resins are used with some success to treat 1,4-dioxane. These large-scale methods are not practical for residential users.

Information about 1,4-dioxane as a residential contaminant and how to treat it is scarce and inconsistent.  For residential treatment the old standby products carbon filtration and reverse osmosis seem to be the best things available, although very little actual testing seems to have been done to establish their effectiveness.
One North Carolina State University researcher says, “Most in-home water filters, including activated carbon filters, don’t remove 1,4-dioxane effectively. Reverse osmosis filters are better, removing a significant portion of the chemical from tap water, but still fall short.”  Not exactly helpful if you’re designing a home treatment strategy, but typical of the information available. One leading internet vendor recommends whole house reverse osmosis at $10,000. Between the lines reading of the not-very-helpful advice on residential treatment indicates that filter carbon works, but not as well as one would hope, that it works best if there is long contact time (large filters and reduced flow rates), and that nutshell carbon seems to work better than coal-based. As for reverse osmosis, everyone agrees that it is effective but no one has established any hard information about rejection percentages.

To plan residential treatment for any contaminant, one needs to consider first  how the contaminant is taken in by humans. In this area, too, there is a disturbing lack of information and a lot of contradictory information about dioxane. Water contaminants can be ingested by drinking contaminated water, or breathed in as a vapor or taken in through the skin. Showering is a common hazard since the contaminant can be taken in through the skin or breathed in if it vaporizes.  Arsenic, to illustrate,  does not evaporate into the air and is not easily absorbed through the skin, so there is little need for “whole house” treatment. Chlorine, conversely, vaporizes easily in the shower and also penetrates the skin, so whole house chlorine treatment is important.

Information about dermal and inhalation exposure to dioxane varies so much that it is essentially useless. The consensus is that it evaporates so quickly that dermal uptake is minimal; but this, of course, makes it more likely that it is breathed in during showering. To complicate the issue, because so many bath products are possible sources of the chemical, it is hard to know how much exposure is avoided by treating the water itself. It certainly makes no sense to install an elaborate and expensive system to remove 1, 4-dioxane from the water you shower with and then use a shampoo that contains the contaminant.

Treatment

Our recommendation for residential 1,4-dioxane protection is the same as for contaminants like fluoride, arsenic, and chromium. Install a high quality reverse osmosis unit that has at least two carbon stages for drinking water. An undersink  RO unit should be a standard feature in all homes.  For the whole house, carbon filtration, either as carbon block cartridge filters or a tank-style backwashing filter, provides broad protection against most contaminants and should reduce exposure to dioxane. We do not believe that installation of over-sized carbon tanks just to treat dioxane is advisable.

dioxanewastedrums

Leaking underground storage tanks at hazardous waste sites and discharges from manufacturing plants are important sources of 1,4-dioxane water contamination. Other significant sources of exposure to the chemical include personal care products like shampoos, deodorants and lotions as well as laundry products and household cleaning products. 

 

 

 

 

 

 

 

 

“Whole House” Reverse Osmosis for Less than $2500

 

The usual operating setup for “whole house” reverse osmosis is to allow the RO unit to produce water into an atmospheric (non- pressurized) storage tank and then use a pump to send the water into the home. This arrangement provides a large storage capacity for treated water (300 to 500 gallons is typical for residences). Standard whole house RO units might be capable of producing up to 1000 gallons or more per day to top off the storage tank as water is withdrawn and pumped to the home. Such setups require pretreatment and posttreatment for the RO unit and a shutoff system for the storage tank, plus the re-pressurization pump to deliver water to the point of use.

The system described on this page is a simple RO unit that uses a pressure tank which is very large version of the storage tanks used on undersink RO units. It is designed for use only in small homes — one or two people with low water use–or in other low use applications like offices, medical offices, or large homes with multiple sinks fed by a single RO unit.

This system features a ready-to-use Axeon 300 gallon-per-day RO unit that includes pre-treatment for sediment and chemicals and has carbon post-filtration built in. It is coupled with a high capacity pressurized RO storage tank.  No RO shut-off or re- pressurization pump is needed. The pressurized storage tank sends water to the point of use and the RO unit turns on automatically to refill the tank.
lt30020

The classy Axeon L1-300 RO unit uses standard-sized housings and membrane for easy replacement. It is a fully automatic unit that shuts off and turns on in response to changes in tank pressure. It is shown here with an optional mounting stand but can also be wall mounted.

 

Installation consists of connecting the RO unit to the storage tank.  We furnish the tee that joins the tank to the RO unit and sends water to the point of use.  Tanks come in 40, 60, and 80 gallon sizes.

 

romate80

ROMate 80 gallon pressurized RO storage tank. Large fiberglass reinforced RO tanks function exactly like well tanks. Water goes in and out through the single pipe at the bottom. 

 

Pages with more information:

Axion L1-300 RO Unit.

RO Tanks.

 

 

EPA Proposes New Regulations For Lead In Drinking Water

  by Paolo Zialcita

This is a National Public Radio news report, issued in late October 2019.

leadpipefromnewark

The Environmental Protection Agency has announced a new proposal that would change how communities test for lead in drinking water. It’s the first major update to the Lead and Copper Rule in nearly 30 years, but it does not go as far as many health advocates had hoped.

The regulations are aimed at stopping people’s water from being contaminated through lead pipes that connect public water supplies to homes. The EPA’s website points out that ingesting lead “can be harmful to human health even at low exposure levels.”

The proposal that was announced Thursday would require water systems to keep a public inventory of where those lead service lines are and help homeowners replace them if their water is found to be contaminated with lead.

If a water test shows dangerous lead levels, utilities would also have to notify their customers within 24 hours.

“By improving protocols for identifying lead, expanding sampling, and strengthening treatment requirements, our proposal would ensure that more water systems proactively take actions to prevent lead exposure, especially in schools, child care facilities, and the most at-risk communities,” EPA Administrator Andrew Wheeler said.