Leak detection for secondary schools
Secondary school leaks usually sit on site distribution mains between blocks or on a heating circuit, and are isolated block by block before the position is fixed acoustically.
The estate at a glance
- Typical sites
- Multiple blocks around a core, sports hall, all-weather pitch, dining hall and kitchen, science block, sometimes a swimming pool and a separate sixth form.
- Typical pipework
- A site distribution network between blocks, often a mixture of MDPE, copper and legacy steel, with sub-meters that may or may not still work.
- Who buys
- School business manager or director of estates, reporting to the head and the trust
- Budget route
- Condition Improvement Fund bid, trust condition allocation, or devolved formula capital for smaller works
- Working window
- Summer works programme for excavation, term time for the survey itself
Why a secondary estate is a distribution problem, not a building problem
A secondary school is a small campus. The water arrives at one point and then travels, often several hundred metres, to blocks that were added in different decades by different contractors. The leak is more often in the ground between buildings than inside any of them.
That changes the survey. On a primary the question is which fitting is running. On a secondary the first question is which branch, and the answer comes from isolating sections at the valves and watching the meter, not from walking the buildings.
The estate profile a survey has to work around
Most secondary sites carry at least three generations of pipework. A 1960s or 1970s core with steel and copper, a 1990s or 2000s extension in MDPE, and a recent block built to current standards. The joints between generations are where failures concentrate.
- Site distribution mains, frequently laid before the current car park or all-weather pitch was built over them
- Sub-meters installed for a previous energy project and never read since
- Sports hall and pool plant, which can mask a leak in the site total because their normal consumption is high and variable
- Science and design technology blocks with dense service runs behind fixed benching
- Distribution spine
- Run under the car park
- Changing block
Plan of a typical secondary school campus showing the incoming main, the distribution runs between blocks, sub-meter positions and the three branches most often responsible for an unexplained night flow.
Where the leak usually is on a secondary site
A secondary site produces two distinct patterns. A sudden, large loss is almost always a distribution main. A slow, persistent rise across a term is almost always a fitting: a cistern overflowing to a gully, a shower valve passing, a lab tap left cracked open.
- Buried distribution mains between blocks, especially under car parks and service roads
- Heating circuits in a single block, identified by a boiler that needs topping up while others do not
- Shower and changing blocks, where the failure is under a tiled floor
- Cisterns discharging to a gully, which look like nothing and cost a great deal
- Irrigation and pitch supplies left pressurised out of season
Isolating a large site down to one branch
The method is subtraction. Read the incoming meter overnight to size the loss, then close section valves one at a time and watch which closure removes the flow. That reduces a fifteen-acre site to a single run within a couple of hours, before any acoustic work starts.
Once the branch is known, correlation along the run fixes the position. Where the run is plastic, or crosses made ground that damps the acoustic signal, tracer gas is used instead: the section is drained, charged with a hydrogen-nitrogen mix and surveyed at the surface.
Safeguarding, DBS and escorting on a large site
A secondary school is easier than a primary in one respect and harder in another. Contractors are a normal sight, so access is routine, but a large open site with several hundred teenagers moving between blocks means unsupervised work in circulation areas is not acceptable during lesson changeover.
Agree in advance who escorts, which gates are used, where the van parks, and whether work can continue through break and lunch. Most delay on a secondary site is access, not detection.
Fitting the work to the school calendar
Survey in term time, dig in the holidays. A distribution main under a car park is a summer job, and the summer programme is set in the spring, so a survey in February or March is what gets the repair into the programme rather than into next year's.
The exception is a leak large enough to affect supply pressure, undermine a surface or reach an electrical intake. That is dealt with when it happens.
What it costs and which budget it comes from
The survey is the cheap part. The repair depends on depth, surface and whether the run can be reused. A dated survey report showing the fault position, the measured loss and the consequence of leaving it is the document that turns a repair into a fundable condition project rather than a maintenance argument.
Single academy trusts and small trusts bid into the Condition Improvement Fund. Large trusts and local authorities receive a School Condition Allocation and prioritise internally.
| Location | Why it happens here |
|---|---|
| Distribution mains running between blocks | particularly where they cross a car park or a service road |
| Heating circuits serving a block that keeps losing pressure while others hold | See the detection approach above. |
| Science laboratory benching | where a service valve behind a bench weeps for months |
| Changing rooms and shower blocks | where a buried run under a tiled floor is invisible until it stains a ceiling below |
| Sports pitch irrigation and pitch-side standpipes | which are frequently left live all year |
| Dining hall and kitchen supplies under fixed equipment | See the detection approach above. |
What to do now
Take a meter reading tonight and another in the morning. If it has moved with the site closed, call and quote the figure; that single number shortens the survey and sets the scope before anyone attends.
Questions schools ask about this setting
Our site is fifteen acres. How long does a survey take?
Sizing the loss and isolating it to a branch is usually the first half day. Fixing the position on that branch is the second. A site with no valve records or with seized valves takes longer, because the isolation step is the one that depends on the school's own infrastructure.
We have sub-meters. Do they help?
Considerably, if they still work and someone knows what each one serves. A working sub-meter on each block turns a whole-site subtraction exercise into a single reading. Confirming what they actually meter is often the most useful hour of the survey.
The boiler in one block keeps losing pressure. Is that a leak?
It is a leak until proven otherwise. A sealed heating system should not need topping up. Before opening any floor, the circuit is pressure tested and the loss rate measured, then located with thermal imaging and tracer gas rather than by lifting screed.
Sources for this page
- Source: Department for Education, Get Information About Schools: all establishment data extract (opens in a new tab) ().
- Source: Department for Education, School capital funding (opens in a new tab) (). This figure is restated annually; check the current edition.
Last reviewed . How this site sources and dates its figures.