Adapting Cistern Liners to Fit Around Pipes and Pumps

Like many other ponds and tanks designed to store water, cisterns rely on a complex fit of plumbing connections and pumps to both fill the storage area and empty it when needed. Without pumps, most cisterns become useless because the water is trapped inside and hard to remove. Few cisterns are located at a high point to rely on gravity release alone since this would also create serious safety risks in case of a flood or collapse. A failed pump just leaves the water underground rather than rushing towards homes and businesses. However, this means that you’ll need to cut a cistern liner multiple times to get it to fit tightly around these penetrations and protrusions. Here are a few tips on fitting cistern liners around these important parts.

Opportunities for Leaks

Every penetration through the liner material creates a new opportunity for a leak. Therefore, minimizing the number of penetrations is also the best way to minimize leaks. Whenever possible, reroute pipes and equipment so it can rest above the surface of the liner or cluster them so they can be treated as a single perforation through the membrane. Inlet pipes, in particular, are easily run so they don’t penetrate the liner at all. If it is necessary to run a vent or overflow pipe through the liner, make sure it’s sized properly so there’s no need to come back and make multiple openings in the material during installation.

Matching Boots and Sealants

Any pipes or plumbing components that penetrate through the flexible liner should be covered with a boot. This is a tight-fitting cover that is easily sealed to the liner material so there’s a watertight seam around each opening. Make sure the boots are made of the same or compatible material as the liner. Using any old rubber pipe boot could result in failed seals that leak without you noticing the problem. Apply the recommended amount of sealant and give the boots plenty of time to cure in place before adding water to the cistern.

Cutting the Liner

Most liners are relatively easy to cut on site, but RPE can be a little tricky due to its reinforced design. Start by getting a component or piece of pipe that matches the fixture and using it as a guide on the liner. Draw around the opening with a light-colored marker for a clear guide on where to cut. Use a fresh blade on a utility knife to cut an X across the center of the opening, then use a sharp pair of utility shears to carefully trim out the shape. Then, installation is as simple as sliding the liner over the penetration, adding any gaskets or boots used for sealing, and finishing off the installation with adhesives and/or clamps.

Battening and Gaskets for Flexible Liners

For concrete and in-ground cisterns, battens are the primary method of installation to hold liners tightly against the walls and floor without adhesives. These plastic or metal bands bolt into the material below and then secure the liner through the use of gaskets. Battens must be placed evenly around the perimeter of the cistern to hold the liner at the correct tension, but openings and plumbing often get in the way. Lay out the various strips of batten and figure out where to place them around these limitations before beginning installation. You may have to reinforce some areas with a double strip of batten to make up for missing sections that would usually run down the length of an entire wall.

Flexible liners are easy to cut and seal around any penetrations or immovable fixtures inside the cistern. Don’t assume that installation will become impossible just because you’re working with a cistern with a lot of protrusions. In fact, cutting and slipping liners over and around pipes is a more reliable way to ensure the cistern is lined than trying to spread liquid coatings. It’s all too easy to miss a patch of liquid coating in a spot obstructed by a pipe. If you’re in need for more installation tips on getting flexible liners to fit into a cistern, or would like our expert installation teams assistance, contact us here at BTL Liners.


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AquaArmor Pond Liner

The most versatile liner on the market today, AquaArmor maximizes protection from harmful UV rays, tear resistance and punctures that cause leaks. Simply the best liner on the market.

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