Compact Retention Tanks



Advanced Retention Tank, outperforms tanks twice its size by relying on enhanced mixing strategies.

Retention tanks play a vital role in water treatment. Their main function is simply to “retain” water being treated long enough for the treatment process to take place. Water treatment chemicals need residence time to do their job. Chlorine, for example, does now work by magic. Whether it is used to control pathogens or perform reactions that facilitate removal of such contaminants as iron and manganese, chlorine usually needs several minutes of contact time with the targeted contaminant. The function of the retention tank is to provide that time.

In residential water treatment, retention tanks of 80 to 120 gallons are commonly installed after the chlorine injection point to allow chlorine time to mix thoroughly with the water and do its work. Oxidizers like ozone and hydrogen peroxide need less time and are used with smaller retention tanks or sometimes with no retention tank at all.

Large tanks are expensive to ship and take up space. A conventional 120 gallon retention tank, for example, is 24″ in diameter x 80″ high. It has to be transported by motor freight, occupies lots of floor space, and typically has a connection size that has to be reduced for use with standard 1″ residential piping. Getting such a tank through a tight door or down stairs into a basement can be a challenge.

Compact Tanks

There are some new tanks on the market that really fill a need. While they aren’t quite the mythical tank that’s bigger on the inside than on the outside, they go a long way in that direction. They require half the floor space of conventional holding tanks and can be set in place without a fork lift.

The new style retention tanks are smaller, easier to transport and generally easier to install. They require a fraction of the floor space of conventional tanks and have been shown to outperform tanks that are much larger in size.

The secret is the inclusion of inner mixing and swirl chambers that can reduce a drop of water to hundreds of micro bubbles, allowing chemical reactions to take place five times as fast as with conventional retention tanks. In a sense, they are tanks with mixing enhancers built into the tank rather than installed externally, like static mixers, for example.


Inner Swirl Chambers and Mixers blend treatment chemicals with the water quickly to cut retention time significantly.

The tanks shown below all use 1″ in/out ports and have a 3/4″ blow-down valve installed at the bottom of the tank for easy clean-out.

Of the tanks listed below, the 12″ unit is recommended for most residential chlorine applications. The smaller tank is for use with ozone and hydrogen peroxide or very low-flow chlorine applications.


Standard, Single-Chamber Tanks

Part Number, Description GPM Port Size Equivalent Conventional Tank Size Price
WH426 – Compact Retention Tank, 10″ X 47″ 25 1″ 80 gallons $465.00
WH420 – Compact Retention Tank, 12″ X 48″  (12″ x 60″ full size including base and cap.) 25 1″ 120 gallons $530.00

These work for most residential applications.  Larger tanks are available, including enhanced versions with multiple mixing chambers.  Please call for information and pricing for larger models.

The tanks on this page are at present “call to order” products that will soon be on our main website.

To call to order, or for more information: 940 382 3814.