High Water Bill Investigation

Purpose

A water bill is an accounting document, not a measurement of your plumbing. This procedure converts it into a measured loss rate at the meter, assigns that rate to a zone, or closes the call with a written explanation of why the bill rose when nothing is leaking. Skip it and the shop sells a leak search on a bill that went up because the read cycle ran 41 days instead of 29, or because last month's read was an estimate and this one is the catch-up. The second failure it prevents is the opposite: a tech who finds one running toilet, calls it solved, and leaves a slab leak still running because nobody re-baselined the meter afterwards.

Scope

Covers the diagnostic visit on a residential or light-commercial metered service where the complaint is consumption, not damage: a bill spike, a utility leak-alert letter, or a customer who noticed the meter turning.

Does not cover locating a loss once it is confirmed and bounded, which is the acoustic and tracer gas leak location SOP, or under a slab, the slab leak detection and access decision SOP. Does not cover a visible active leak, which is a repair call and may be the burst pipe emergency response SOP. Does not cover well systems, which have no meter and are investigated through pump cycling under the well pump service call SOP. Nobody in the shop disputes a utility's billing on the customer's behalf; the shop supplies measurements and the customer files.

Roles and the handoff

Procedure

1. Walk the property for an active loss before opening the paperwork. Look at the heater pan, the softener drain, under sinks, the crawlspace hatch and the yard. Acceptance: a written yes or no on visible water, and on standing water near a receptacle, panel or appliance cord. Stop rule: standing water near electrical equipment ends the walk, nobody enters that space, and work resumes only after a qualified person under 29 CFR 1910.332 and 1910.399 isolates circuits per 29 CFR 1910.333(b)(2). Hazard: this step is the hazard, which is why it runs first.

2. Read the bill in gallons per day, never in dollars or in totals. Acceptance: four numbers written down, being the billing period in days, the consumption, the same period a year earlier with its own day count, and whether each read was actual or estimated. Stop rule: a period longer than the prior one, or an estimated prior read, means the headline multiple is not the consumption multiple, so recompute per day before anyone touches a valve. Hazard: none here, a desk step done at the kitchen table; record it as checked rather than blank.

3. Baseline the house to a true zero. Close every fixture, unplug or valve off the ice maker, switch the irrigation controller to off, and lock out the softener so it cannot regenerate mid-test. Acceptance: a written list of every consumer locked out, and a still leak indicator or register for one full minute before timing starts. Stop rule: a register that moves during lockout means something is still drawing, so find it rather than starting the clock. Hazard: a softener locked out is also a softener somebody must put back, so tag the bypass now rather than trusting memory.

4. Time the register and print the arithmetic. Read, wait a timed interval of at least 15 minutes, read again. Acceptance: a gallons-per-minute figure with both register readings and the elapsed minutes shown, converted at 7.48 gal per cu ft where the register reads cubic feet. Stop rule: a still register proves flow below what that meter resolves, not zero, so record the resolution limit and move to a pressure hold rather than writing "no leak". Hazard: never enter a meter pit or vault, a permit-required confined space under 29 CFR 1910.146 and a different crew; read from grade with the lid hooked.

5. Split inside from outside at the house valve. Close the valve just downstream of the meter and repeat the timed read. Acceptance: the register stops, putting the loss inside the building, or holds near the step 4 rate, putting it in the buried service. Stop rule: a partial fall means two paths, so keep isolating rather than choosing the larger one. Hazard: buried valve boxes hold wasps, spiders and broken lids, so look in with a light and turn with a key rather than a hand.

6. Dye test every toilet, not the one the customer mentions. Drop dye in each tank, do not flush, and time it. Acceptance: no colour in any bowl after 15 minutes; any bowl showing colour, with the time it appeared, is a flapper or flush valve seat. Stop rule: colour in more than one bowl means the whole group gets replaced rather than the first one found. Hazard: dye tablets stain skin and irritate eyes, so glove up, and never leave a dyed tank in a house where a pet drinks from the bowl.

7. Account for the intermittent consumers before you blame a pipe. Softener regeneration frequency and setting, pool or spa auto-fill, evaporative cooler, humidifier, and any irrigation zone with a stuck valve. Acceptance: each named with its per-cycle volume read from the equipment data plate and its cycles per week, so the weekly gallons are a figure and not an opinion. Stop rule: a softener on a timer rather than a demand meter is itself a finding and gets written down even when the leak is elsewhere. Hazard: brine tanks and their discharge are a slip and an irritant, so no reaching into the brine well bare-handed.

8. Split hot from cold only where a loss survives steps 5 through 7. Close the heater cold inlet and repeat the timed read. Acceptance: the rate falls to zero, putting the loss on the hot side, or holds, putting it on the cold. Stop rule: where the loss is already fully accounted for, write "not required" with the reason rather than running a test whose result you will not use. Hazard: piping at the heater sits at 120 to 140 F and 140 F water scalds in a couple of seconds, so glove up and open no fitting here.

9. Put every consumer back and prove the house works. Reopen the house valve slowly with a high fixture running, restore the softener from bypass, return the irrigation controller to its schedule, reconnect the ice maker. Acceptance: static within about 5 psi of the arrival reading at the same gauge point, softener in service with regeneration re-enabled, controller showing its original program, and every toilet refilled and quiet. Stop rule: any item on the step 3 lockout list you cannot restore is called out in writing before you leave the property. Hazard: repressurizing puts a tech's face at fittings, so crack the valve a quarter turn and stand off the plane of any joint; a softener left in bypass sends untreated water to a heater the customer will not notice until the scale bill arrives.

The record this produces

Eight fields: the visible-loss and standing-water answers; the four billing figures with consumption restated in gallons per day; the step 3 lockout list; the measured rate with both readings and the elapsed minutes; the inside-or-outside verdict; each toilet's dye result with its time; each intermittent consumer with its per-cycle volume and cycles per week; and the restore verification. The disposition is one of three: a bounded loss handed to a location SOP, a found and corrected consumer, or no measurable loss with the billing arithmetic that explains the rise. That third one is the record a customer takes to the utility, and it is the reason the readings matter more than the conclusion.

One worked pass, including a step that fails

A four-bedroom house, two adults and two teenagers, city meter, softener, no pool. The customer's bill is 2.4 times the same month last year and the utility mailed a leak alert.

Step 1: no visible water, no standing water near electrical equipment, logged 10:20.

Step 2: this cycle billed 18,400 gal over 41 days; the same month last year billed 7,700 gal over 30 days. Per day that is 18,400 divided by 41, or 449 gal, against 7,700 divided by 30, or 257 gal. So consumption per day is 449 divided by 257, about 1.75 times, not the 2.4 times the totals suggest. The prior read was estimated, which is why the period ran long.

Step 3 FAILS. With fixtures closed the register still creeps. The softener is mid-regeneration on a timer setting nobody mentioned. Stop rule taken: the clock does not start. The softener is bypassed and tagged, the ice maker valved off, the irrigation controller switched off, and the register watched until it is still for a full minute.

Step 4: register at 8812.0 cu ft, then 8813.2 cu ft after a timed 20 minutes. That is 1.2 cu ft; at 7.48 gal per cu ft, 1.2 times 7.48 is 9.0 gal, and 9.0 divided by 20 is 0.45 gpm.

Step 5: the house valve closes and the register stops. The loss is inside.

Step 6: three toilets dyed. The primary bath bowl shows colour at 12 minutes; the other two are clear at 15. One flapper, replaced on the visit.

Step 7: softener regenerating on a 2-day timer, per-cycle volume read from its data plate as 45 gal, so about 158 gal a week. Written down as a finding and quoted for a demand-metered head, whether or not it caused the spike.

Step 8: not required, with the reason recorded, because the post-repair re-baseline in step 4 returns a still register for a full 20 minutes.

The interpretive check matters more than any single number here. The measured 0.45 gpm is 648 gal per day, and 648 times 41 days is 26,568 gal, which is larger than the entire 18,400 gal the customer was billed. A continuous loss cannot exceed the total consumption of the period, so this flapper was intermittent or started partway through the cycle. The excess over the prior-year baseline is 449 minus 257, or 192 gal per day, and 192 times 41 is about 7,870 gal. That is the figure the record carries. The 648 is written as a rate measured at 10:55 on the day of the visit, explicitly not extrapolated across the period.

Step 9: softener back in service and regeneration re-enabled, irrigation controller returned to its original program, ice maker reconnected. Static reads 63 psi at the laundry bib against 65 psi on arrival, a 2 psi difference and inside the 5 psi acceptance. All three toilets refilled and quiet.

When the site does not match this procedure

The meter is not accessible or is inside a locked vault. No entry. Book the utility to pull a read, and substitute a pressure hold on the isolated house line so the visit still produces a number.

A shared meter serving several units. No per-address rate exists. Say so plainly, isolate per unit with pressure holds, and do not let a landlord attribute the whole bill to one tenant on your paperwork.

The customer wants the bill disputed. The shop supplies readings and a repair date. The claim is the customer's to file, and most utilities require both before they will consider an adjustment.

Consumption is real and there is no leak. A new occupant, a filled pool, a summer irrigation program or a teenager home from school will do it. The finding is a no-loss disposition with the per-day arithmetic, not a leak search sold to close the ticket honestly.

References

• 29 CFR 1910.146 for permit-required confined spaces, which covers meter pits and vaults; 29 CFR 1910.333(b)(2) for electrical work practices, with qualified-person scope at 29 CFR 1910.332 and 1910.399.
• The water utility's own adjustment policy, which typically requires a documented loss rate and a repair date, and which the customer files rather than the shop.
• The softener manufacturer's data plate for per-regeneration volume, read on site rather than assumed.
• See related: the acoustic and tracer gas leak location SOP and the slab leak detection and access decision SOP for what happens after a loss is bounded.