How to Find (and Fix) a Pond Leak

December 16, 2018
Containment Pond

Do you suspect that your pond has a leak in it? Do you see seepage, marshy, or extremely green areas where they weren’t before? You might have a leak in your pond and the sooner you find and fix it, the better. Ponds are typically closed systems, which means there should never be any leakage from it.

Here is how to find out if your pond has a leak and how to fix it.

  1. First of all, check the season and the weather. Could the decline in the level of the pond be from evaporation from a long, hot, dry summer? (Ponds can lose up to 1 INCH of water per day during the hot, dry summer months!) During spring, the snow melt could cause an overflow in the pond, which you are assuming is a leak but is perfectly normal for that time of year. Once you have determined that it’s not season-related, then you will need to check other areas of the pond.
  2. Check for rodent tunnels near the edge of the pond and areas where rocks have noticeably shifted or moved. Sometimes rodents such as rats, chipmunks, and ground squirrels dig tunnels that can disturb the pond liner or other parts of the pond mechanisms. If you see any rocks or areas around the edge of the pond that have shifted or moved, check those areas carefully.
  3. Check your outlet pipe. Water should only be coming out of the inside of the pipe—if you see any water coming from the outside of the pipe, you will need to repack the pipe with at least one foot of pure clay in order to get the water to stop leaking. Also make sure that you don’t have a metal piping, which could be rusting and will need to be completely replaced with PVC.
  4. Check your pond pump by turning it off. If the water level continues to drop, this means that the leak is definitely in your main pond basin. If the water level does not continue to drop, then you can assume that the main basin is fine and that the leak is either in the plumbing or in the waterfall or stream. Inspect all of your plumbing including all joints to make sure there is no seepage from them. Then look at your waterfall and stream for any leaks. Often, there can be plant matter or other obstructions that raise the water level and cause an overflow over the liner’s edge.
  5. Check your mechanical pond skimmer connection. Turn the pump off and fill your pond to its normal level. Mark the initial water level. Keep the pump off for 12-24 hours and then take a second reading. If the pond remains full after that time, the mechanical pond skinner connection is watertight and not the source of the leak.
  6. Check your waterfall stream. Check the waterfall box and connections, the underground plumbing, and check valve. If the waterfall filter level remains constant, then these elements are not the cause of the leak. Water loss occurs when the pump is on and water is in motion, which is typical around the sides of a waterfall or the sides of a stream. Check the left and right sides of each waterfall area carefully, as well as the edges of the pond liner along the waterfall or pond stream.
  7. Check the pond liner itself. Check the edges to make sure that the pond liner has not sunk down or that rocks have not been displaced. Inspect the liner all along the water level to find any irregularity, large tears, or tiny punctures. Some large pond liners are not as durable as others – make sure that you investigate your options before building out your pond in order to choose the correct type of liner for its specific environment. If you have any older pond and do not know which liner is in there, you may have to drain the pond to check the liner by visual inspection.

Most leaks occur because of a settled or crumpled liner or water is being diverted over the liner’s edge. Holes in the liner are rarely the reason for a leak, especially if the pond has held water dependably before this occurrence. If you find that your pond is leaking on a consistent basis, then it may be time to drain the pond and install a new liner. You may want to read our comprehensive pond liner installation guide.

Also, persistent leaks may be a sign that you’ve chosen a poor pond liner material. Not every pond liner material is right for every job, so make sure your using a good geombembrane for your application. Also, liner fabrication is a big factor in how likely you are to encounter leaks. Factors like using a single sheet versus multiple sheets, and factory welding versus in-field welding are critical in determining the risk of leaks.

We’re happy to guide you in both of these areas. Contact us if you have questions.

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