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Keep watch for swimming pool leaks
swimming pool

Swimming pools naturally lose some water to evaporation, splash-out and to backwash wastewater. However, if you're routinely adding more than two inches of water to your pool per week, you probably have a leak that is worth spending some time, and possibly money, to repair.  Pools are built to be watertight but sealants will deteriorate and other parts of your pool can shift, settle, or just plain wear out. Pools can leak through any of the fittings, accessories, plumbing, or even right through the shell. It is important to repair leaks, not only to save water, heat, and chemicals, but to also prevent undermining the pool’s structural components and washing away fill dirt that supports the pool walls and deck.

Leak detection is a highly specialized branch of the pool industry.  However, most leak issues are inexpensive to repair and a professional will be equipped to assist you if you are unable to repair it yourself. If you suspect a leak, review the following things before calling for service:


This may indicate a pressure-side return leak. With the filter pump on, the plumbing on the pressure side (after the pump) is under pressure. This can open up small drips into spraying gushers. Check the waste or backwash line for water consistently running. One inch of your pool water can equal 500 gallons. Check downhill from a pool, looking for weepers where underground leakage is surfacing. Check for soft or wet spots in the yard, on the side of the pool where the plumbing returns water to the pool.


This usually indicates a suction-side leak, or on the pipes that bring water from the pool. With the filter pump on, the plumbing on the suction side is under vacuum. Air can be drawn in through otherwise leaking voids. You may notice air in the pump basket (if you have a clear lid), air bubbling out of the return lines, or air repeatedly built up inside the filter tank. Use tape or a pencil to mark water levels.


This does not rule out leaks in the plumbing, but turns a suspicious eye on the shell of the pool, looking for cracks in the plaster or tears in the vinyl. Look closely at the tile line and inside of the skimmer(s). The most common leak is a separation between the plastic skimmer and the concrete pool. This is easily fixed with some pool putty. If you see something that looks like a crack, drop some test dye near it with the pump shut off and water still to see if the dye is sucked into the crack. Under water lights can, and do, leak as well, especially the conduit that runs from the light niche to the junction box. Filling the opening of the conduit in the back of the light niche with pool putty, black butyl tape, or using a cord stopper are ways to fix this problem.


Take a walk outside the pool deck and between the pool and the equipment pad. Check for wet soil and eroded areas. If your pool has a downhill slope near the pool, walk down the hill to see if you can notice water weeping from the hillside.


Most pool leaks are not in the underground plumbing, although it’s every pool owner’s worst fear, a large backhoe coming in and ripping up the pool deck. It does happen occasionally, that a leak occurs at a pipe connector under the pool deck, or beneath the skimmer, but repair rarely involves a backhoe. To determine if the pipes are leaking, the simple way is to shut off the pump and plug all the lines. If it keeps leaking, we know it’s not the pipes. If it stops leaking, the plugs can be removed individually to see when leaking continues, although some pools only leak with the pump running. Once narrowed down, a pool plumbing pressure test can be performed on the underground plumbing pipes, to see which ones are leaking.

In most cases, a small 3’x3’ hole can be cut into the deck, to repair the break, but very rarely does the entire run of pipe need to be replaced. If it did, it would likely be abandoned, and a new pipe run in its place.


Nearly all in-ground concrete pools will develop leaking problems at the skimmer throat at some point. Expansion and contraction of the pool and deck moves the skimmer slightly, breaking the cement seal between the pool wall and the skimmer. The seal is on both sides and the bottom of the front of the skimmer, and can be dye tested (with pump off), to determine if water is being drawn into cracks around the front edge of the skimmer opening. Pool Putty is often used as a temporary repair to seal up leaking concrete skimmers

For questions about water conservation, contact Municipal Services at 209-668-5590 or visit the City’s website at Brought to you by the City of Turlock Municipal Services Department.




Summer watering schedule in effect: Odd numbered residences can water on Wednesdays and Sundays. Even numbered residences can water on Tuesdays and Saturdays. No watering is allowed between the hours of 9 a.m. and 7 p.m.