How Can I Tell If My Swimming Pool Is Leaking?

This morning one of my customers, a pool service guy, came to me with a frustrated look on his face. One of the pools that he takes care of seems to be losing water and uses a lot of chemicals compared to his other clients. He asked me “how can I tell if it’s a leak or just evaporating?”

Why Does It Matter?

This is an important question, especially for a service guy who is supplying chemicals to a pool that may well be dumping them into the ground. We all know these chemicals are expensive so who can afford to flush them away like old bath water? It is equally as important for the homeowner to know that she is not spending hundreds every month hydrating the Earth’s crust with her expensive water.

Leaks can be expensive but they can also cause all kinds of damage. When the water level in a pool drops, often the pump will lose its prime because it’s drawing air through the skimmer instead of water. When most pumps run dry, they overheat and the plastic parts, along with the PVC plumbing, will virtually melt and become misshapen. Now the pump won’t hold or move water and the PVC pipes begin leaking. If the leak is underground, the flowing water through the sand or dirt will create washouts or mini sinkholes causing decks, walkways, or foundations to settle or sag and eventually crack. The list of possibilities goes on but you get my drift and I haven’t even mentioned the number of gallons of precious water that are wasted each year through unidentified leaks.

Where is the Water Going?

On the other hand, water DOES evaporate. “How much?” you may ask. Well, I can’t really answer that because there are many variables. Ambient humidity is a huge factor as are air temperature, water temperature and wind. I’ve seen pools lose up to 1/2 “ a day from evaporation in extreme conditions.

First, we need to determine if the pool is really leaking or if the water is being lost some other way like splash-out, evaporation or maybe there’s a parade of pachyderms coming by at night to quench their thirst. I remember a pool years ago in Indiana that was in a raised back yard. I probably visited this pool 5 times or more, diving the pool, digging up pipes and basically going crazy trying to figure out how this pool was losing water until one day it occurred to me that every time I came out, there was a garden hose hanging into the pool. Kinda normal, I guess for a leaking pool to be constantly in need of water but when I followed the hose back to the spigot, what I saw made my jaw drop. Apparently the homeowner didn’t think that the little rubber washer in the  hose connection was important because with the faucet turned off, there was probably a gallon or two a minute siphoning out of the pool onto the ground at the foundation! That’s about 3,000 gallons a day!

So, How Can You Tell?

There’s a simple test that anyone can do to confirm a leaking pool. It’s called the Bucket Test. Sounds like a great name for a movie, don’t ya think? This will only confirm a leak if we can successfully eliminate outside causes such as the aforementioned siphon or the herd of elephants that uses your pool for a nightly watering trough.

First, and don’t faint on me here, you’ll need a bucket. A tall bucket works best, like a 5 gallon paint bucket. Put some kind of weight in it like a brick and fill it partially with water. Place the bucket on your pool steps so that the top is above water level and then fill the bucket until the water level in the bucket is the same as the level outside the bucket (in the pool). Turn off any fountains or waterfalls (Fountains and sprays evaporate much faster that pooled water) and otherwise run your pool as you normally would. Wait 24 hours and check the levels. The idea is that both the bucket and the pool are subjected to the same conditions with regard to temperature, humidity, wind, rain, etc. so if we’re evaporating, they should evaporate at the same rate. If the pool is leaking, the pool level will be lower than the bucket level…make sense?

By the way, if the water in the bucket went down there’s either a hole in the bucket, Dear Liza, Dear Liza,  or you have a thirsty dog!

Written by Hank Graham