House Pressure Survey and PRV Assessment
Purpose
Static pressure is not one number and a regulator verdict cannot be made from one reading. This procedure produces four readings taken at one gauge point, being street-side static, house static at rest, house static after a stated no-draw period, and flowing pressure at a stated draw, plus a yes or no on whether the system is closed. From those, a regulator is either holding, passing, restricting or absent, and each of those is a different job. Skip it and the shop replaces a perfectly good regulator because the customer said the pressure was bad, then gets the callback anyway because the real fault was 40 ft of restricted galvanized on the other side of it.
Scope
Covers the survey visit on a residential or light-commercial potable supply where the complaint is pressure, banging, a weeping relief valve, or a regulator of unknown age, and the deliverable is a verdict rather than a part.
Does not cover replacing or setting a regulator, which the pressure reducing valve replacement SOP owns and which this one hands to. Does not cover the heater-driven pressure rise on a closed system, which is the thermal expansion and pressure complaint investigation SOP; this procedure deliberately removes heat input from its creep test so the two do not get confused. Does not cover distribution restriction inside the building, which the pipe material identification and condition report SOP owns and which shares this procedure's flow gate but attributes it differently. Does not cover well systems, which are governed by a pressure switch and a tank rather than a regulator.
Roles and the handoff
| Role | What they own | The handoff |
|---|---|---|
| Dispatcher | The complaint in the customer's words, and whether a regulator is known to exist | Puts the complaint verbatim on the ticket, because banging and weak flow lead to different gates |
| Technician | One gauge point, all four readings, the closed-system answer | Returns four numbers at one location plus the draw used, never a single "pressure is fine" |
| Lead or owner | Whether the verdict supports a regulator replacement or routes elsewhere | Signs it, since replacing a regulator that was holding is the expensive version of this mistake |
| Office | Filing the four readings against the address | Supplies the baseline next time, which is what makes a later creep argument decidable |
Procedure
Locate the shutoff and check the bib before a gauge goes on it. Acceptance: the main located and proved to close and reopen, and the chosen bib inspected for corroded threads and a sound stem. Stop rule: no shutoff that holds ends the survey, and that becomes the shutoff location and labeling visit. Hazard: a gauge on corroded hose bib threads becomes a projectile at street pressure, so back the bib body with a second wrench, never stand square in front of the gauge, and bring pressure on slowly.
Fix one gauge point and use it for every reading. Acceptance: the gauge location named in the record, being a hose bib, laundry box or heater drain, and the gauge marked in increments no coarser than 2 psi. Stop rule: readings taken at two different points are not comparable, because elevation and intervening restriction both shift them, so a survey that had to move the gauge records both locations and does not subtract across them. Hazard: none here, a fitting threaded on a cold bib; record it as checked rather than blank.
Read street-side static upstream of the regulator. Acceptance: a number in psi from a bib or tap ahead of the regulator, taken with all fixtures closed. Stop rule: where nothing upstream is accessible, the field reads unavailable and is obtained from the utility or a temporary tee, never inferred from the downstream reading, because the whole regulator verdict rests on the difference between the two sides. Hazard: an outdoor bib on the street side sees full main pressure, commonly well above the house side, so treat it as the higher-energy connection and stand clear.
Read house static at rest. Acceptance: a number in psi at the step 2 point with every fixture closed and no appliance drawing. Stop rule: above 80 psi the model codes require an approved pressure reducing valve on the water distribution system, at IPC Section 604.8 and UPC Section 608.2 in the edition your jurisdiction has adopted, so a house over that figure with no regulator is a code finding and not merely a comfort complaint. Hazard: none here; record it as checked rather than blank.
Run the creep test with heat input removed. Switch the water heater off at its disconnect or gas control, close everything, lock out the ice maker and softener, and leave the gauge on for a stated 30 minutes. Acceptance: the rise over 30 minutes, with a rise over 5 psi meaning the regulator is passing street pressure through. Stop rule: any draw during the window voids the test, so lock the consumers out and re-run rather than explaining the number away. Hazard: a heater switched off is a heater somebody must switch back on, so tag the disconnect now, and never test creep by capping or restraining a relief valve.
Read flowing pressure at a stated draw, at the same point. Open two fixtures at the far end of the system and read the gauge while they run. Acceptance: static minus flowing at that named draw, with a drop over about 20 psi indicating restriction. Stop rule: that gate says restriction exists, not where it is, so it is never written as a regulator verdict on its own. Hazard: opening far fixtures fast slams the system, so open them gradually, and expect hot-side water at 120 to 140 F where the draw includes a hot tap, which scalds in a couple of seconds.
Locate the restriction by reading both sides during the same draw. Acceptance: the upstream drop and the downstream drop, both recorded during the same run. Stop rule: an upstream side that holds while the downstream side collapses puts the restriction at or below the regulator; an upstream side that falls with it puts it in the service or the main and takes the regulator off the hook entirely. Hazard: this reading requires a second gauge or a second trip to the street side while water is running, so the route is walked first and nothing is left running unattended in a finished space.
Answer the closed-system question and write the verdict. Acceptance: a yes or no on a check valve, backflow assembly or regulator with an integral check, a yes or no on an expansion tank, and one verdict of holding, passing, restricting or absent with the readings that decided it. Stop rule: a closed system with no working expansion control is a separate finding and routes to the thermal expansion and pressure complaint investigation SOP even when the regulator itself is fine. Hazard: none here, a verdict at the table; discharge it rather than leaving it blank.
Put the heat and the water back and prove the protections work. Remove the gauge, restore the heater at its disconnect or gas control, restore the ice maker and softener, and reopen anything closed. Acceptance: static within about 5 psi of the arrival reading at the step 2 point, the bib proved to shut and hold with no drip, the heater confirmed running through one full cycle, and the relief valve confirmed free with its discharge piping intact and terminating as found. Stop rule: any item you switched off that you cannot restore is called out in writing before you leave. Hazard: this is the step that puts fuel or power and pressure back into an occupied building, so the relief valve is verified unobstructed before the heater fires, and no test gauge, plug or cap leaves the site still installed.
The record this produces
Seven fields: the gauge point and gauge resolution; street-side static or the word unavailable; house static at rest; the 30 minute creep figure with heat input confirmed off; flowing pressure at a named draw with the drop computed; the upstream and downstream drops from the same run; and the closed-system answer with the verdict.
The four pressures are the baseline. A year from now, when the same customer says the pressure changed, the shop can say what it was, at which bib, with what running, and settle in one sentence an argument that otherwise runs for a week.
One worked pass, including a step that fails
A 1996 two-storey house. Complaint: banging when the washer shuts off, and the water heater relief valve weeping most evenings.
Step 1: main located at the garage, closes and reopens. Laundry bib threads sound.
Step 2: gauge point is the laundry box bib, gauge marked in 1 psi increments.
Step 3: an outdoor bib ahead of the regulator gives street-side static of 118 psi with everything closed.
Step 4: house static at rest at the laundry bib reads 74 psi, under the 80 psi figure the model codes set, so no code finding on static.
Step 5: heater breaker off and tagged, ice maker valved off, everything closed. Gauge reads 74 psi at the start and 76 psi at 30 minutes. That is a 2 psi rise, inside the 5 psi gate, so the regulator is not passing.
Step 6 FAILS. With the upstairs lavatory and the upstairs tub both open, the laundry bib reads 40 psi against the 74 psi at rest. That is 74 minus 40, or a 34 psi drop at a two-fixture draw, well over the 20 psi gate. The step's own stop rule applies: restriction exists, but this number does not say where.
Step 7: the same draw is repeated with a second gauge on the street-side bib. Upstream reads 112 psi against 118 psi at rest, a 6 psi drop, so the service and the main are delivering. Downstream falls 34 psi over the same run. The restriction sits at or below the regulator.
Step 8: a dual check at the meter makes the system closed, and there is no expansion tank anywhere. Two findings written, not one. The regulator is graded restricting on the 34 psi against 6 psi split and routed to the pressure reducing valve replacement SOP. The closed system with no expansion control is routed to the thermal expansion and pressure complaint investigation SOP, which owns the weeping relief valve; the banging and the weeping turn out to have different owners.
Step 9: gauge off, heater breaker restored and tagged clear, ice maker reopened. Static reads 73 psi at the laundry bib against 74 psi on arrival, a 1 psi difference and inside the 5 psi acceptance. The bib shuts with no drip. The heater is watched through one full cycle to confirm it fires and satisfies, and the relief valve and its discharge piping are confirmed free and terminating as found before the tech leaves.
When the site does not match this procedure
No accessible tap upstream of the regulator. Step 3 reads unavailable and step 7 cannot split the drop. The verdict then goes no further than restriction present, location undetermined, with a recommendation to fit a test tee. Do not convict a regulator on a downstream reading alone.
No regulator at all and static over 80 psi. That is a code finding under the adopted IPC or UPC section, and installing one is an alteration that turns the system closed, so expansion control is part of the same scope rather than a later visit.
Well system. There is no regulator and no street side. The four readings become cut-in and cut-out pressures at the switch, the tank pre-charge, and flowing pressure at a stated draw, which is the well pump service call SOP rather than this one.
Multifamily with a house regulator serving several units. Readings taken in one unit include every riser between it and the regulator. Say so in the record and take the survey at the regulator itself where access allows.
References
- IPC Section 604.8 and UPC Section 608.2, which require an approved pressure reducing valve where static water distribution pressure exceeds 80 psi, in the edition your authority having jurisdiction has adopted.
- The regulator manufacturer's published flow and pressure data for the specific model, which sets what a given valve should deliver at a given draw.
- See related: the pressure reducing valve replacement SOP, the thermal expansion and pressure complaint investigation SOP, and the pipe material identification and condition report SOP, which shares this flow gate but attributes it to the distribution rather than the valve.