What a temporary water supply
on site actually costs.
The cost splits three ways, and only one of the three is the water. The connection is quoted, the consumption is metered, and the compliance is the part that gets left out of the price.
Published ·9 min read·Written by Darshan Parmar, Founder
The cost of a temporary water supply splits three ways: getting the connection in, paying for the water that runs through it, and proving the water is fit to drink. The first is quoted, the second is metered, and the third is the one that gets left out of the tender and then turns up as a certificate the main contractor wants at handover.
The three costs, and why only one is obvious
Ask most people what a site water supply costs and they will answer with the connection charge, because that is the number on the quotation. It is usually the largest single figure and it is the one that arrives first, so it dominates.
It is also the only one of the three that is fixed and knowable in advance. Consumption is a function of how long the job runs and what the water is used for. Compliance is a recurring obligation that continues for as long as the system is live, and it is entirely absent from the connection quotation, which is precisely why it gets forgotten.
| Component | When it lands | Where the figure comes from |
|---|---|---|
| Connection | Once, before work starts | A quotation from your water undertaker under its published charging arrangements |
| Consumption | Monthly, for the life of the job | Metered volume at the undertaker's tariff, plus any wastewater element |
| Compliance | At commissioning, then on a cycle | Your own or a specialist's labour, plus laboratory sampling fees |
No prices appear in that table on purpose. Connection charges are set regionally by each water undertaker under its own charging arrangements, and they vary with main size, the distance from the main to the site boundary, whether the highway has to be opened, and what reinstatement the highway authority requires. A figure quoted here would be wrong for most readers. What is stable is the structure, and knowing the structure is what stops a tender being priced on one third of the cost.
Getting the connection
A temporary supply for construction purposes is arranged with the water undertaker for the area under the Water Industry Act 1991. There is a duty to make a connection for domestic purposes on request, subject to conditions and to payment, and construction use is generally handled as a non-household supply arranged with a retailer in England, since the non-household market opened to competition in 2017. That split catches people out: in England the pipe and the connection are the wholesaler's, but the account and the tariff are a retailer's, and they are two conversations rather than one.
The practical sequence runs like this. An application goes in with a site plan and an estimate of demand. The undertaker surveys, confirms where the main is and what it can deliver, and issues a quotation. The quotation covers the connection itself, any main laying required to reach the site, highway opening and reinstatement, and the meter. Once accepted and paid, the work is scheduled, and that scheduling is the item that damages programmes, because it sits outside your control entirely.
The two decisions that move the number most are both taken early. Whether the temporary supply is laid on the alignment of the permanent one, so that the same excavation and connection serve both, and whether the route crosses land you do not control, because a wayleave or easement adds a legal negotiation to an engineering job.
Standpipes, bowsers and when they make sense
Not every site takes a connection. For short programmes, or where the connection cannot be delivered inside the mobilisation window, the alternatives are a licensed standpipe from a hydrant or a bowser filled and delivered.
A standpipe is licensed by the water undertaker and metered, and using a hydrant without one is both an offence and a genuine safety issue, because uncontrolled hydrant operation can disturb mains and draw sediment into the network. Licences carry conditions about backflow prevention for exactly that reason.
Bowsers remove the connection problem and introduce a storage problem. Water standing in a tank in summer is a legionella risk in a way that water moving through a live main is not, which moves cost from the connection line into the compliance line rather than removing it.
The honest comparison is on total programme cost rather than on mobilisation cost. A standpipe or bowser is cheaper to start and more expensive to run. A connection is the reverse. The crossover point depends on programme length and consumption, and on most jobs over a few months the connection wins, which is why the decision belongs at tender rather than at mobilisation.
The compliance estate nobody prices
This is the section worth the reading time, because it is where firms in this business lose margin.
A temporary water system that people will drink from, wash in, or that will eventually connect to a permanent installation, carries obligations that do not stop when the pipe is in the ground.
Disinfection and the chlorination certificate
New pipework, altered pipework, pipework that has been repaired in a way that may have introduced contamination, and pipework that has stood unused all need disinfecting before use. The record of that is a chlorination certificate: the certificate number, the service and location, the standard the disinfection was carried out to, the test duration, the individual readings before and after flushing, and signatures from the person who carried out the test and the person who accepted the result.
That certificate is a handover document. A main contractor asks for it at practical completion and a duty holder files it as evidence of a clean start. It is also the single item most likely to have been emailed to a project manager who has since left, which is a problem that only becomes visible on the day it is requested.
Sampling
Disinfection is proved by sampling, and sampling means laboratory fees and turnaround time. Both belong in the programme as well as the price, because a result that fails means reflushing, redisinfecting and resampling, and the handover date does not move to accommodate it.
Fittings and backflow
The Water Supply (Water Fittings) Regulations 1999 apply to a temporary installation just as they do to a permanent one. Fittings must be of an appropriate quality and standard and must not cause contamination, waste, misuse or undue consumption. Backflow prevention appropriate to the fluid category is the requirement that bites hardest on construction sites, because a site is full of exactly the sort of connection the regulations exist to prevent: a hose in a bucket of something, upstream of a supply that other people drink from.
Legionella
Where water is stored, or stands at a temperature that suits the organism, legionella control applies. ACOP L8 is an approved code of practice rather than a statute, which means a duty holder may do something else provided it is equally effective, and in practice everybody follows it. On a construction site the risk is concentrated in the arrangements people think of as harmless: bowsers, storage tanks in welfare units, and long dead legs left in a system that was commissioned early and used lightly.
Sentinel outlet temperature checks are a two minute job. The risk is never that the work is hard. It is that the date passes, and on a construction site with a changing population of people responsible, dates pass easily.
Drinking water is a separate question
CDM 2015 Schedule 2 requires an adequate supply of wholesome drinking water at readily accessible and suitable places, conspicuously marked where necessary. "Wholesome" is doing real work in that sentence.
Water from a live mains connection, through compliant fittings, is wholesome without further argument. Water from a bowser, or from a temporary system that has not been disinfected and sampled, is not, and providing it as drinking water is a welfare breach as well as a water quality one. That is the link between this article and site welfare and what Schedule 2 actually requires: the welfare duty assumes a water supply that somebody has taken responsibility for.
Pricing it properly at tender
For a firm supplying temporary site services, water is tendered against measured rates, so the margin is set before anybody turns up. Five items are consistently underpriced or omitted.
- The recurring compliance labour. Temperature checks, filter changes and periodic sampling across a long programme. This is the largest omission and it grows with programme length rather than with the size of the installation.
- Laboratory fees. Real money, per sample, and more than once if a result fails.
- Alterations. Every time the site layout changes and the temporary main is extended or diverted, the altered section needs disinfecting and certifying again. On a rate-based contract that is a variation to be measured and signed, not a favour.
- Standing water management. Flushing regimes for parts of the system that are commissioned early and used lightly.
- The strike. Disconnection, meter removal, reinstatement, and returning the standpipe or bowser. Metered supplies keep charging until the account is formally closed, which is the same failure described in off-hire, and the charges that keep running.
The commercial half sits where the rest of the job does: the temporary water installation is estimated against a named rate library, valued on site as it proceeds against those same rates, and each alteration is measured and signed as a variation rather than absorbed. The compliance half is held as records against the project. Chlorination certificates are structured records with the readings as individual pass or fail fields and two signature blocks, rendered as a PDF from the record on demand, so the certificate can still be produced against the right job years after the person who issued it has left. Water testing and filter change dates sit in the reminders engine with the vehicle MOTs and the accreditation renewals, colouring red once a date has passed and amber inside thirty days. One qualification worth stating: those water hygiene registers are proven in the temporary site services business that has run on Unibuild since 2016, and they sit empty in the construction contracting deployment, because that firm does not carry the obligation. The capability is real and we will demonstrate it, but it is demonstrated in the deployment that uses it.
Where to start, on Monday
Take the last temporary water installation you completed and add up what you actually spent on it after the connection was in: the flushing, the sampling, the fees, the alterations, the temperature checks and the disconnection. Compare that with what the tender allowed for those items.
On most jobs the tender allowed for very little of it, because the connection quotation was treated as the cost of the supply. That difference is not a pricing error to be embarrassed about. It is the number to put in the next tender.
Sources
Checked against the source rather than against commentary. Where a schedule, a rate or a threshold is definitive on a government site, read it there.
- Water Industry Act 1991 legislation.gov.uk
- Water Supply (Water Fittings) Regulations 1999 legislation.gov.uk
- HSE: Legionnaires disease, the control of legionella bacteria in water systems (ACOP L8) Health and Safety Executive
The follow-up questions.
The other two services a site cannot open without are covered in temporary electrical supply and site welfare.
How much does a temporary water supply to a construction site cost?+
Do you need a licence to use a standpipe on a hydrant?+
When is a chlorination certificate needed?+
Can site staff drink from a bowser?+
Does the temporary supply have to be metered?+
Price the whole obligation, not the connection.
The tender is won on rates. The margin is decided by whether the recurring compliance was in those rates or discovered afterwards.
- Forty-five minutes, weekdays, from tomorrow.
- Nothing to prepare. Bring a job number and we mock that job up.
- You drive it. There is no slide deck.
- You keep what you saw as a 14-day trial. No card.
More from Insights.
Temporary electrical supply, and the paperwork behind itWhy site power runs at 110 volts, what has to be inspected every three months, and why the isolation permit is the document that decides whether anybody is allowed to work on it.Read it →
Site welfare, and what Schedule 2 actually requiresToilets, washing, drinking water, somewhere to change and somewhere to sit down. The list is short, it is legally specific, and "so far as is reasonably practicable" does not apply to most of it.Read it →
The certificates that expire without anybody noticingInsurance, cards, plant inspections, training and first aid all run out on different dates, and nothing about your file changes on the day one of them does. What has to watch them.Read it →All 3 articles on site services.