Leak detection & underwater repair · Thornhatch & the Gorse Headland

An inch a week is the weather. Two is a phone call.

Sounding Line finds and fixes the water your pool is quietly losing — lines pressure-tested one by one, dye tracing the seams, hydrophones listening through the shell for the hiss of a leak no eye can see. Most repairs happen underwater with the pool full: no drain, no re-plaster, no month off. The diagnosis is a flat menu and the finding is a fact before it is an invoice.

Services & rates

The diagnosis menu, flat

The menu is flat because the finding is not a sales process: the audit names the leak, the leak names the fix, and you can hand our sheet to any firm on the coast. About one audit in five ends with “evaporation only — nothing to fix”, and we answer those calls gladly, because being told your pool is fine is worth the drive.

The bucket test, taughtfree

Taught over the phone in five minutes — the answer to “leak or weather” before anyone drives

Full hydrostatic audit$385 flat

Bucket test, meter read, shell inspection, all lines pressure-tested one at a time

Line isolation & sonic tracefrom $290

Pressure decay per line, hydrophone sweep, dye and seam survey — the leak named to the foot

Underwater shell repairfrom $640

Crack injection and patching with the pool FULL — no drain-down, no re-plaster

Fitting & skimmer repairsfrom $420

Return and light niches, skimmer throats and gaskets — the four places pools actually leak

Plumbing reroutefrom $2,800

A failed line abandoned and replaced around the deck, not under it

Diagnosis figures

The find sheet, in figures

1,412
leaks named to the foot since 2015
83%
repaired underwater with the pool full — no drain-down
48 hr
response across the Headland, season permitting
1 in 5
audits that end “evaporation only” — and we drive home

What we do

What Sounding Line finds & fixes

The forensics

Pressure testing line by line — returns, skimmer, main drain, spa loop, feature feeds — until one of them refuses to hold and names itself. Then the hydrophone: a stethoscope for the shell, pressed to the plaster and moved foot by foot until the leak’s hiss is loud enough to point at. The find sheet carries the pressures, the bearings and the map; you keep it whatever you do next.

The forensics
The underwater repairs

The underwater repairs

Most leaks are fittings, seams and cracks — all of them repairable with the pool full, by divers, in a visit: injected epoxies in the crack, re-seated niche and skimmer gaskets, patched vinyl where a liner meets a fitting. No drain-down, no pebble or plaster re-do, no month with a hole in the yard. The pool keeps swimming while it gets well.

The reroutes & the stubborn ones

When a buried line is the culprit and the deck argues, we abandon it in place and reroute around — a new pipe at the surface of the equipment trench, not an excavation through your patio. And for the leak that hides under the shell, the pressure graphs over time tell us when to stop testing and start reading the ground: the honest end of one road and the start of another.

The reroutes & the stubborn ones

The rescue doctrine

Facts before invoices

The trade’s dirty secret is that leak work is priced by mystery: the longer nobody can name the leak, the more the hours bill. Ours runs the other way — the audit is flat because the finding is a fact, the fix is quoted from the find sheet, and the bucket test that starts it all is free over the phone. A pool losing water is stressful enough without writing blank cheques into the stress.

Named, or the audit is free

If the hydrostatic audit cannot name your leak, you pay nothing and keep the sheet — the pressures, the readings, the map, all of it useful to whoever tries next. It has happened eleven times in nine years, and four of those pools called us back within a season when the leak grew an honest symptom.

How a leak is found

The trace, in four moves

1

Measure

Bucket test and meter read: how much is weather, how much is leak, how many gallons a day the pool is really losing.

2

Pressurise

Every line sealed, charged and watched — the one that decays is the one that is lying to you.

3

Listen

Hydrophone sweep of the shell and deck, foot by foot, chasing the hiss until it is loud enough to point at.

4

Name & fix

The find sheet with the leak drawn on it, the flat fix price beside it, and most repairs done underwater that visit.

2025 — 2026, the Headland

Found, fixed, full the whole time

Six finds from last season, photographed at the equipment pad and the seam. Captions name the leak and the fix — because on this page the diagnosis is the portfolio.

The Wickham shell
The Wickham shell — forty-foot crack, injected, pool never drained
Gorse Headland audit
Gorse Headland audit — return line named to the foot in an afternoon
Skimmer throat re-seat
Skimmer throat re-seat — the classic leak, the classic fix
The reroute at Ferry End
The reroute at Ferry End — abandoned line, new pipe, patio intact
Diver at the light niche
Diver at the light niche — gasket renewed, water never dropped
The find sheet
The find sheet — pressures, bearings, and the leak drawn in red

Fair questions

Questions from the deep end

The five every Headland kitchen reaches while watching the water line creep down. The rescue line answers seven to five, and the bucket is in the truck.

How do I know it is a leak and not evaporation?

The bucket test, and it costs nothing: fill a bucket to the water line, set it on the step, and compare the levels after a day or two. Pool down more than bucket means water leaving through somewhere other than the sky — an inch a week is weather on the Headland, two is a phone call. We teach it over the phone before we ever book the audit.

The pool only drops when the pump runs. What does that mean?

That is the leak raising its hand. Falling with the pump ON points at the pressure side — a return line or a fitting under working pressure; falling only with the pump OFF points at the suction side, skimmer or main drain. It halves the search before we arrive, and it is the first question the rescue line asks.

Will you have to drain my pool?

Almost certainly not: eighty-three percent of our repairs happen underwater with the pool full — crack injections, re-seated fittings, skimmer throats, vinyl patches. Draining is the last resort, not the method, and on the rare shell that genuinely needs it we say why in writing and schedule around your swimming, not ours.

What if the leak is under the deck or the shell?

Then the pressure graphs earn their keep. Lines are tested to isolation first — a leak under the patio usually means one reroute around it rather than through it, and a leak suspected under the shell is chased by listening and by process of elimination before anyone talks about excavation. The find sheet records every step, including the ones we did not need.

What does the repair do to my finish?

Nothing you will find later: injected cracks in a pebble or plaster shell are trimmed flush and cured underwater, vinyl patches are colour-matched and welded at the seam, and no repair we do voids a finish warranty — we repair UNDER them, not through them. If a leak has gone unfixed long enough to damage the finish itself, the find sheet says so and the refinish conversation happens with facts, not fear.

Two firms told us the water level was “probably the season”. Sounding Line taught me the bucket test on the phone, booked the audit for the Tuesday, and had the return line named to the foot by lunch — the find sheet has the pressure graph and a red arrow. The diver fixed it that afternoon with the pool full, and we swam that evening. I framed a plumbing diagram. Again: a plumbing diagram.
G. Wickham-Ferreira · Pressure-side repair, the Wickham shell
Our pool dropped two inches a week for a summer and I stopped trusting it. The audit found a skimmer throat gasket and a light niche — both fixed underwater in one visit, both on the flat menu at the price printed. The sheet they left would let any company on the coast do the same work, which is either honest or foolish, and it worked out honest.
The Oduya family · Skimmer & niche repairs, Gorse Headland
The buried return under our patio was the diagnosis nobody wanted. They pressure-tested every line, showed me the one decaying, and rerouted AROUND the deck in two days instead of through it in two weeks. The old line stays abandoned under the stone where it belongs, the new one runs where it can be seen, and the pool has held its level for fourteen months.
R. Marchetti-Osei · Line reroute, Ferry End

Bucket tests taught over the phone, any time · (555) 028-6092 · trace@soundingline.example

Where is the water going?

Send the address and what the level has been doing — inches per week, pump on or off, bucket test if you have run one. The audit is flat, the finding is a fact, and most fixes happen underwater before the week is out. trace@soundingline.example

The leak report