The Bucket Test: How to Check if Your Pool Is Leaking

Before you call anyone about a suspected leak, there is a simple test you can do yourself that settles the most important question: is your pool actually leaking, or is it just losing water to evaporation? It is called the bucket test, it costs nothing, and it takes about a day. Here is exactly how to do it.

Why the bucket test works

Every open pool loses water to evaporation, and in a Cape Town summer with the south-easter blowing, that can be 3 to 5mm a day. The trick is separating that normal loss from a genuine leak. The bucket test does this elegantly: it lets a bucket of pool water evaporate under exactly the same conditions as the pool, so you can compare the two directly.

What you need

• A clean bucket
• Pool water
• A waterproof marker or tape
• 24 hours of normal weather

Step by step

1. Fill the bucket about two-thirds full with water from the pool.
2. Stand it on a pool step so it sits partly submerged. This makes sure the bucket water and the pool water share the same sun, wind and temperature.
3. Mark both levels. Mark the water level inside the bucket and the pool water level on the outside of the bucket or on the pool wall.
4. Leave the pump running as normal for the first 24 hours, then check. Mark how far each level has dropped.

Reading the result

If the pool and the bucket have dropped by roughly the same amount, you are looking at evaporation, not a leak. If the pool has dropped noticeably more than the bucket, you have a leak. The bigger the gap, the bigger the leak.

If the pool level falls faster than the bucket, the difference is your leak, plain and simple.

A useful refinement

You can run the test twice to narrow down where the leak is. Do it once with the pump running and once with it off. If the pool loses more water with the pump running, the leak is likely on the pressure side, in the return plumbing. If it loses more with the pump off, the leak is more likely in the shell or on the suction side. This is a clue, not a diagnosis, but it helps.

What to do next

The bucket test tells you whether you have a leak, but not where it is. Finding the exact source is where professional equipment comes in: electronic listening, pressure testing and dye testing pinpoint it without breaking up your paving. If your bucket test confirms a loss, that is the time to call in a specialist rather than guessing and digging.

Frequently asked questions