If your pool dye test found nothing, the leak may be somewhere dye cannot reach: the underground plumbing between your equipment pad and the pool, or the equipment itself. Dye only shows a leak at an opening you can hold it next to, in still water. The next step is a pressure test of each pool line, one at a time, then acoustic listening along any line that will not hold pressure. That is how a Master Plumber finds a pool leak without tearing up the deck to go looking.
Why October is a good time to sort this out in Allen
Evaporation slows down as the nights cool off. In July, sun and wind can take enough water out of an Allen pool to hide a small leak. By October, if you are still adding water as often as you did in August, the extra water is going somewhere. If your pool has an autofill, you may not notice at all until the water bill shows up.
Fall is also an easier time to dig and repair an underground line than the middle of winter, and a leak found now is a few months less water soaking the soil under your deck.
Pool dye test found nothing? First confirm water loss
If you have not done a bucket test yet, start there. Set a bucket on the pool step, fill it with pool water to the same level as the pool, and mark both water lines. Leave the pump off and check after 24 hours. If the pool dropped more than the bucket, you are losing water to more than evaporation. The City of Tampa Water Department’s official pool-leak guidance describes the same evaporation-comparison method and recommends shutting down pool systems and automatic refill devices during the test.
It also helps to repeat the test with the pump running. If the pool loses more with the pump on, that points toward the plumbing that is under pressure while the system runs.
Why a dye test can come back clean
A dye test is a good tool. It just has limits.
- It only shows leaks at openings you test. If a pipe is cracked ten feet under the deck, the water may pull through the fitting too slowly to move a ribbon of dye.
- The water has to be completely still. A pump that just shut off, a breeze or a swimmer moving nearby can scatter the dye and hide a weak pull.
- Some lines only leak with the pump running. With the pump off for a dye test, a pressure-side line may hardly leak at all.
- Equipment leaks never show up in the pool. A drip at a valve, union, filter or heater on the equipment pad happens outside the water.
A negative dye test is still useful. It helps rule out the shell, lights, skimmer throats and fittings, so the testing can move on to the plumbing.
How a Master Plumber tests pool plumbing
1. Check the equipment pad
We look at the pump seal, valves, unions, filter and heater for drips, damp soil or mineral crust. It is the quickest thing to rule out.
2. Dye test the shell and fittings
If it has not been done well already, we get in the water and dye test the lights, returns, skimmer throats and housings, main drains, spa jets, spa returns and any cracks we can see.
3. Pressure test each line on its own
We plug each line at the pool end, pressurize it from the equipment side, and watch a gauge. A line that holds is ruled out. A line that drops is leaking. We work through the system one line at a time: the main drain lines, the skimmer lines, the spa jets, the spa drain and the pool returns. Testing them separately is what turns “somewhere in the plumbing” into one specific line.
4. Work out the route
Pool lines rarely run in a straight line from the equipment to the fitting. We trace or work out the path the failing line takes under the deck so we know where to listen.
5. Listen along that line with a geophone
With the line under pressure, we set a geophone down every foot or two along its route. Water and air escaping a cracked pipe make a gurgle or hiss that is loudest right at the break.
This step needs quiet. Construction down the street, a barking dog, music next door, even someone shuffling their feet on the deck can sound like a leak through the headphones. We will ask everyone to stand still, and we check any suspicious sound more than once before we mark it.
6. Mark it and write it up
We mark the leak on the deck and document every test in your written Certified Master Plumber Report: which lines held, which line failed, and where the break is. You or your pool company can take that report straight to the repair.
A Real Job in Richardson: Dye Test Clean, Return Line Failed
A large pool in Richardson was losing about 4 inches of water a day. I swam the pool and dye tested everything: the lights, the returns, the spa returns and jets, every skimmer basket, housing and drain, and every crack we could find. A couple of times it looked like the dye moved. Each time it turned out to be nothing.
So we moved to pressure testing. The main drain lines held. The skimmer lines held. The spa jets held, and so did the spa main drain. The pool return line did not. It lost about 1.2 pounds of air pressure every 3 minutes.
That is a small leak, and it was hard to hear. I worked the route from the equipment pad toward each return with the geophone and line tracing. Construction nearby, a barking dog, music and our own feet all gave false readings, so I had everyone stand still more than once. Finally, on the line close to the fence, I heard a clear gurgle. The repair crew tunneled about 3 feet under the pool deck to reach the pipe and made the repair without breaking the deck. When we retested, the gauge held steady.
What it costs
Leak detection starts at $339, which covers the first two hours on site, and additional time is $175 per hour. Every visit includes a written Certified Master Plumber Report.
A pool with a spa, several return lines and multiple skimmers has more lines to test, so it can run past two hours. A visit that takes three hours, for example, would be $339 plus $175, or $514. The repair is separate and depends on where the break is and how deep it sits under the deck.
How to get ready for the visit
- Keep the water at its normal level, in the middle of the skimmer opening.
- Write down how much water you have been adding and how often.
- If you have an autofill, turn it off a day or two ahead so the real loss shows.
- Clear a path to the equipment pad and keep pets inside.
- Have a recent water bill handy so we can compare usage before and after.
When to call
- The bucket test shows the pool dropping faster than the bucket
- Your dye test came back clean and the pool keeps dropping
- You see wet soil, a soft spot or a new crack near the deck or equipment
- The pump basket fills with air, or the pump loses prime
- You are adding water more often than you did last fall
Call or text 972-333-5448 to schedule pool leak detection in Allen.
Frequently asked questions
Can the leak be in the plumbing even if the pool shell looks fine?
Yes. Many pool leaks are in the underground return, skimmer or drain lines, where you can’t see them and dye can’t reach them.
Do you have to drain the pool to test it?
No. Dye testing, pressure testing and acoustic listening are all done with the pool full and at its normal level.
Will you have to break up my deck?
Testing does not require any digging. The repair usually needs one opening at the spot we mark, which is much smaller than digging to search.
Why test every line separately?
Because a single pressure test of the whole system only tells you something is leaking. Testing line by line tells you which pipe, so the listening and the repair happen in the right place.