Pool & Spa Leak Detection in DeKalb, IL
DeKalb pools work hard for a few months and then sit through a long freeze. That cycle is exactly what finds weaknesses: a skimmer throat that cracked over winter, a return fitting that loosened, a liner seam that let go, an underground return line that heaved. Owners usually notice in June, when the autofill runs constantly and the chemical bill stops making sense.
Before anything else, rule out evaporation. In a typical northern Illinois summer, an uncovered pool loses roughly a quarter inch a day to evaporation, more in hot dry wind. Losing half an inch or more daily, or any measurable loss under a cover, is a leak.
On this page
Telling a leak from normal water loss
The bucket test says leak
Fill a bucket with pool water, set it on a step so the inside and outside levels match, mark both, and leave it 24 hours with the pump running normally. If the pool drops more than the bucket, you are losing water to a leak rather than to the air.
Autofill runs constantly
An autofill masks a leak beautifully, which is why many pool leaks in DeKalb are found by the water bill rather than by the water line.
Water loss changes when the pump runs
Losing more with the pump on points to pressure-side plumbing — returns. Losing more with the pump off points to suction-side plumbing or the structure itself.
Soggy or sinking ground around the deck
Underground plumbing leaks saturate the base under pavers and concrete, which then settles and cracks.
Air bubbles from the returns
Air entering on the suction side, often at the pump lid, the skimmer throat or a cracked suction line.
Chemical demand keeps rising
Water leaving means chemicals leaving. Constant rebalancing with no other explanation is a leak symptom.
Visible cracks at the skimmer or light niche
Freeze damage concentrates at the skimmer throat and the light niche because that is where the structure changes material.
A liner that wrinkles, floats or shifts
Water behind a vinyl liner lifts it. If the liner has changed shape since spring opening, water is getting behind it.
How we find a pool leak
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Establish the actual loss rate
We measure the drop over a controlled period with the pump on and then off. That single comparison sorts structural leaks from plumbing leaks and saves hours of hunting.
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Dye test the shell, fittings and seams
With the pump off and the water dead still, a dye applied at suspect points shows the draw of a leak clearly. We work the skimmer throat, returns, main drain, light niche, steps, tile line, liner seams and any visible crack.
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Pressure test each line separately
Skimmer, main drain and each return get isolated, plugged and pressurized individually. A line that will not hold pressure is the leaking line, full stop — no guessing about which pipe to dig.
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Acoustically locate the leak along the buried line
Once we know which line leaks, we pressurize it with air or water and trace it with listening equipment to pinpoint the failure under the deck or lawn, so the repair is one small opening rather than a replaced run.
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Inspect the equipment pad
Pump seals, filter clamps, heater headers, valve bodies and unions leak more often than the pool does, and those repairs are cheap. We always rule the pad out before we suggest opening concrete.
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Report with a repair plan
You get the location, the cause and a quote. Liner patch, fitting replacement, skimmer repair, line re-route or sectional plumbing repair, priced honestly against what the pool is worth.
Where DeKalb pools leak most often
The skimmer
Number one by a wide margin in freeze climates. Water in the skimmer throat freezes and expands, separating the plastic skimmer body from the surrounding concrete or opening a crack at the faceplate. Dye testing at the throat finds it in minutes.
Return and suction line penetrations
The fitting where a pipe passes through the shell is a material transition, and material transitions move at different rates through a freeze cycle. Gaskets fail, threads crack, the surrounding gunite develops a hairline.
Buried plumbing under the deck
Clay soil that heaves in a hard winter can shift a line enough to open a glued joint. This is the leak that produces the classic sinking-paver symptom.
Vinyl liner seams and around fittings
Liners get brittle with age and UV exposure. Most liner leaks show up at a seam, at a fitting gasket or at the step fasteners rather than in open field.
Light niche conduit
Water finds the conduit at the light niche and travels away from the pool. It is an easy leak to miss because the water does not appear anywhere near the pool.
Spas, hot tubs and water features
The same methods work on in-ground spas, spillover spas, attached hot tubs and decorative water features. Spas leak most commonly at jet bodies, at the heater union, at the pump seal and at the spillover transition where the spa shares plumbing with the pool. Because a spa holds far less water, a leak that would be trivial in a pool empties a spa in days.
A note on winterization: the majority of the spring leak calls we take in DeKalb trace to a winterizing miss — a line not fully blown out, a missing skimmer bottle, a plug not seated. Getting the closing right is cheaper than any leak locate, and we would rather tell you that in September than find the crack in May.
Common questions
Around a quarter inch a day from evaporation for an uncovered pool in summer, varying with heat, wind and humidity. Under a cover, loss should be minimal. Anything above a half inch a day, or any consistent loss under a cover, warrants a bucket test and then a call.
Yes, and we prefer not to drain it. Draining a vinyl-liner pool risks the liner shifting, and draining a fiberglass or concrete pool with a high water table can float or damage the shell. Dye testing, line pressure testing and acoustic locating are all done with the pool full.
Structural and liner inspections need water and reasonable temperatures, so most shell work waits for the season. Pressure testing of buried lines and equipment pad diagnostics can often be done earlier. If your pool lost water over the winter, book early — spring opening is the busiest window for this work in DeKalb County.
It can. Water escaping under a deck washes out the base material, which settles and cracks the deck. Water against a pool shell from the outside can push a liner off the wall or, in extreme cases with a high water table, affect the shell itself. Heat and chemicals go out with the water too, so the running cost is higher than the gallons alone suggest.
We quote it on the call. A full residential pool inspection with dye testing, line pressure testing and acoustic locating costs more than a single-symptom visit — for instance a known skimmer crack you just want confirmed. Either way you hear the number before we travel.
Both, in most cases. Fitting replacement, skimmer repairs, liner patching and plumbing line repairs are within our scope. For full liner replacement or major shell resurfacing we will hand you our locate report and recommend a specialist rather than pretend it is our trade.
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Think you have a leak? Call and we will find it today.
Same-day appointments across DeKalb and next-door response for active flooding. No digging or demolition until we know exactly where the leak is.
Leak line, answered 24 hours
(815) 849-0091Call nowOne call does it. We work out what is likely wrong on the phone, quote before we come out, and book you in on the same call.