Working with United Utilities to prevent costly water loss from pool top‑up systems
As part of a series of water efficiency visits across leisure, education and hospitality facilities, United Utilities recently identified an issue during one pool inspection that highlights a wider risk for operators: a pool water make‑up valve left open.
During the visit, the manual pool water make-up valve, which would normally be opened only when the system requires top-up water, had been inadvertently left open. This allowed fresh water to flow continuously, potentially for days, leading to unnecessary water loss and avoidable operational costs.
Although this was a single case, it demonstrates how easily this can happen, particularly on sites with manual control of the make-up system, and how significant the impact can be if it goes unnoticed.
Luke Brewer‑Nevitt, Water Efficiency Delivery Manager at United Utilities, explains why the finding is important:
’Even a single incident shows how quickly water loss can escalate. An open pool water make-up valve can waste thousands of litres a day, increasing water, energy and chemical costs.
Our simple 10‑minute check will help technicians and operators maintain performance and avoid unintentional water waste.”
United Utilities’ 10‑minute visual check
A quick routine that can be added to existing pool plant inspections, where manual make-up valves are installed,
- Locate the pool water make-up valve.
- Confirm the isolation valve is closed as the default position.
- Check backflow protection (non‑return or double‑check valves) are present, labelled, and functional.
- Listen for unexpected water flow or a continuously open control valve.
- Review water meter readings for unexplained increases.
Additional good practice tips
- Use clear signage such as Pool make-up – open only when make-up water required .
- Introduce tags or sign‑off sheets for anyone who opens the valve.
- Include valve‑position checks in daily or weekly plant inspections.
- Verify that backflow protection devices work correctly.
- Install a low‑cost sub‑meter on the make‑up line.
Automated make-up systems
More modern pool water treatment and filtration systems may incorporate automated pool make-up systems on level-deck design pools. The make-up water isolation valve is automated – either a solenoid valve or an electrically actuated valve. This valve would be actuated by the filtration control system, when the balance tank level control system calls for water. As a failsafe, the isolation valve can also signal the building management system (BMS) to signal whether the valve is open or closed.
Overflows
Level-deck swimming pools generally have a balance tank; the make-up water is supplied to the balance tank to top up the system when required. In some instances, balance tanks have been fitted with an overflow, connected to the foul water discharge system. Overflows are not recommended: if the balance tank is operating at a high level, or if there is an issue with the balance tank level control system, there is a risk of continuous discharge of fresh water to drain. And there is the risk of backflow from the foul drainage system, which will contaminate the pool water and put bathers at risk.