Finding a buried or above-ground cistern can be surprising and somewhat dismaying for home and business owners. Once the vault or tank has been identified as a freshwater cistern and not a septic or gas tank, it’s time to decide if it’s worth repairing and using. On-site storage, for rainwater or freshwater supplies, is worth a small investment to restore; especially when compared to the cost of putting in a new tank or pond. A well-maintained, safe cistern can boost property values even if you don’t have a specific use for it right now. If you’re wondering if your cistern is too far gone to line and repair, try these steps to assess its condition.
Stability of Original Structure
The first step in determining the value and safety of an existing cistern is to examine its overall structure. For above-ground tanks, this includes the exterior, interior, and any supports or pads holding it up. Major damage to the structure, like cracked pads, bent or collapsed frames, broken weld seams on tanks, and deep rust that penetrates through the material all generally cost more to fix than the cistern is worth. For in-ground structures, check for signs of soil movement or erosion around the edges of the vault or pond. Look for soil voids and extensively cracked concrete or steel reinforcements that will take a lot of work to remove and replace. Small cracks are easily patched and then covered with a new liner, but structural instability is usually too expensive to fix and requires a replacement or retirement of the cistern.
Testing for Leaks
Testing for and locating leaks is the next step in assessing a cistern’s condition. Dye tests are commonly performed by professionals, but they’re hard to do on your own since it’s tricky to see where the dyes are moving without high intensity lights. Above-ground tanks are easier to test since you can use a dye in the tank and look for signs of it along every seam and exterior surface. For in ground and buried cisterns, tightness testing is usually used. The tank or pond is completely drained, then it is filled with a specific amount of water. When the water is pumped out again, the amount lost is measured. If enough water is lost to indicate a leak, electric or acoustic testing is used. For small residential cisterns, it’s easiest to visually check for bubbles forming along the walls as you fill it. Puddles and mud around the cistern also indicate water escaping through the soil. If you can’t visually see any large cracks or sources of leaks in an underground or pond cistern, they’re likely small enough to be solved with the application of a flexible liner.
Risk of Leaks or Water Exposure
Consider what could become damaged if an older cistern suddenly leaks or collapses. If the pond or tank is located far from other structures and already has a good secondary containment system, it’s likely worth repairing even if there’s a chance of failure. Large cisterns located close to residential and commercial areas create much more risk from even a small leak, meaning they should be retired if there’s a chance that lining won’t be enough to restore the feature.
Some old and abandoned cisterns are built from materials that aren’t ideal for holding water, even for irrigation use. Many stacked stone, unreinforced concrete, and aluminum cisterns are abandoned in favor of newer models that offer better water control and fewer leaching issues. Unless there’s a desire to keep one of these cisterns around for aesthetic value, they’re best retired and filled instead of being put to a new use. Cisterns that aren’t a good choice for drinking or irrigation water storage can still be re-purposed as water features with the addition of fountains or careful reshaping to make them more visible from the ground.
Need for the Water
If there’s a strong need for the water near the existing cistern, it’s obviously worth spending more time and effort to repair. Consider how using a cistern for watering acres of grass or flushing toilets could help cut water costs. On an industrial level, repairing a single damaged cistern could add thousands to millions of gallons of storage space. Weigh the need for a steady water supply against the cost of repairs when making your decision.
Retired and filled-in cisterns still deserve lining to prevent them from accumulating or losing water during heavy rainstorms. Applying liner over the top of a filled cistern is the best way to keep it dry and stable. The same materials work just as well for restoring an older cistern that’s leaking and needs a new liner. Whatever you plan to do, you can find the right products to accomplish your cistern goals here at BTL Liners.