Cooling tower water treatment, done properly.
We look after cooling towers and evaporative condensers for facilities teams, data centres, hospitals and industry. Treatment, dosing, monitoring, cleaning and records, all to ACOP L8 and HSG274 Part 1, explained in plain English.
- GuidanceACOP L8
- TechnicalHSG274 Part 1
- SamplesUKAS-accredited lab
- 01Fan & drift eliminators
- 02Spray distribution
- 03Fill pack
- 04Pond & strainers
- 05Dosing & bleed control
- 06Sample point
Three documents your cooling tower lives by.
If you're the dutyholder for a site with wet cooling, these are the ones that matter. We work to all three, and we'll happily walk you through what they mean for your site.
ACOP L8
The Approved Code of Practice for controlling Legionella in water systems. It sets out the dutyholder's responsibilities: assess the risk, have a written scheme, appoint a responsible person, monitor and keep records.
HSG274 Part 1
The technical guidance for evaporative cooling systems. It covers treatment, monitoring frequencies, action levels for TVC and Legionella, and how to decide how often to clean and disinfect. The second edition was published in 2024.
Notification Regulations 1992
The Notification of Cooling Towers and Evaporative Condensers Regulations 1992 require you to tell your local authority, in writing, about wet cooling towers and evaporative condensers on your premises.
Everything your cooling system needs, from one team.
Use us for the lot, or just the parts you need. Either way you get engineers who know evaporative cooling inside out and won't bury you in jargon.
Water treatment programmes
A programme built around your plant: chemistry, dosing, bleed control, monitoring and visits, all set out in plain English.
Find out more 02Chemical dosing & biocide control
Dosing equipment supply and maintenance, biocide regimes and conductivity-controlled bleed that actually does what it says.
Find out more 03Monitoring & Legionella sampling
Weekly and monthly checks, dip slides and TVCs, and quarterly Legionella samples analysed by a UKAS-accredited lab.
Find out more 04Cleaning & disinfection
Scheduled clean and disinfection, set by inspection and risk: pond, fill, drift eliminators, distribution and casing.
Find out more 05Risk assessments & written schemes
Site-specific Legionella risk assessments for evaporative cooling, plus a written scheme your team can actually follow.
Find out more 06Log books & compliance records
Log books set up and kept current, with results, certificates, cleaning records and actions in one place.
Find out more 07Positive result response
A clear plan when results come back high: review controls, disinfect if needed, resample, record.
Find out more 08Shutdown, start-up & commissioning
Safe shutdowns, start-up after idle periods and commissioning of new or refurbished cooling plant.
Find out moreFour ways a cooling system goes wrong.
A good programme keeps all four in balance. They're connected, so fixing one while ignoring another rarely works for long.
- 01Inhibitor + bleed
Scale
Hardness salts concentrate as water evaporates and coat the hottest surfaces, cutting efficiency and sheltering bacteria.
- 02Inhibitor
Corrosion
Pipework, heat exchangers and casings slowly eaten away. Corrosion products also feed bacterial growth.
- 03Dispersant + cleaning
Fouling
Dust, pollen and debris pulled in from the air settle in the pond and fill, soaking up biocide.
- 04Biocides
Microbiology
General bacteria, biofilm and Legionella. Kept down with a biocide regime and checked by dip slides and lab samples.
Built for sites where cooling can't fail.
Different buildings, different pressures. We plan the work around how your site actually runs. All sectors
Data centres
Uptime matters more than anything, so treatment, cleaning and sampling are planned around redundancy and change control.
Hospitals and healthcare
Vulnerable people nearby means less room for error. We support your Water Safety Group with clear records and quick escalation.
Manufacturing and process
Process cooling, evaporative condensers and plant that can't easily stop. We treat for the process as well as the Legionella risk.
Food and drink processing
Evaporative condensers on refrigeration plant are common here. We keep them clean and treated without disrupting cold chain.
Commercial buildings
Offices, retail and mixed-use buildings with rooftop towers, often near air intakes, windows and busy streets.
M&E contractors and FM companies
We work as your specialist water treatment partner, on your sites, to your reporting standards.
From first call to a system that's under control.
No drawn-out onboarding. Here's what happens when you bring us in.
Talk it through
A quick call about your plant, how it's used and what's worrying you. We'll ask for any existing records.
Site survey
An engineer looks at the system, the dosing kit and the log book, and checks your risk assessment is current.
Programme and quote
We set out the treatment, visit schedule and monitoring we recommend, with a clear, itemised price.
Set up
Dosing commissioned, chemicals delivered, log book organised, and a clean and disinfection booked if it's due.
Routine visits
Testing, sampling, adjustments and a short report every time. If something's off, you'll hear from us straight away.
What you can count on.
We're not going to promise you the moon. What we will do is turn up when we say, do the job properly, and tell you plainly what we've found.
If you've ever had a treatment report that was just a page of numbers with no explanation, you'll notice the difference.
Results explained, not just emailed
Every visit report says what we tested, what it means and what happens next.
Lab samples to a UKAS-accredited lab
Legionella samples are analysed by an accredited laboratory, with certificates for your file.
Log book kept current
We update your records on every visit, so you're always ready for an inspection.
One team for the whole system
Treatment, dosing, cleaning, risk assessments and records, without juggling contractors.
Straight answers when something's wrong
A high count gets a phone call and a plan, not a line buried in a report.
Latest advice
Practical guidance on cooling tower compliance, written the way we'd explain it on site. All articles
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Heatwaves and cooling towers: why hot spells test your controls
Why hot weather puts cooling tower Legionella controls under pressure, what tends to go wrong in a heatwave and a practical checklist before the next one.
Read article -
Taking over a site with cooling towers: a handover checklist
New FM contract, new lease or newly acquired site with cooling towers? A practical handover checklist covering records, roles, notification and the plant.
Read article -
Bleed-off and conductivity control: getting cycles of concentration right
What cycles of concentration mean, how bleed-off and conductivity control work, and what happens when the setpoint is too high or too low.
Read article
Which laws and guidance apply to cooling towers?
Four main pieces. The Health and Safety at Work etc. Act 1974 and COSHH set the general duty to control the risk from Legionella. ACOP L8 explains how to meet that duty, and HSG274 Part 1 gives the technical detail for evaporative cooling systems. On top of that, the Notification of Cooling Towers and Evaporative Condensers Regulations 1992 say the local authority must know your tower exists.
Do I need to notify the local authority about my cooling tower?
Yes. Under the Notification of Cooling Towers and Evaporative Condensers Regulations 1992, you must tell your local authority in writing about any wet cooling tower or evaporative condenser on your premises, and tell them again when one is taken out of use. Councils usually have a form for it. Our article on notifying the council walks through it.
How often should a cooling tower be cleaned?
As often as inspection shows it's fouling. HSG274 Part 1 (2024) gives typical intervals of at least every three months for a tower in a dirty environment, at least twice a year for air conditioning comfort cooling, and at least every 12 months for a clean industrial system. Many sites clean six-monthly as a precaution. Your risk assessment sets the actual figure. More in our article on cleaning frequency.
How often should a cooling tower be tested for Legionella?
At least quarterly. HSG274 Part 1 says routine Legionella sampling should be done at least every three months, and more often in some situations: weekly at first when commissioning a system or starting a new treatment programme, after a positive result, or where the risk assessment calls for it because vulnerable people are nearby. See our monitoring and sampling service.
What Legionella count is a problem?
Anything above 100 cfu/litre needs action, and above 1,000 cfu/litre needs it immediately. Between 100 and 1,000, HSG274 Part 1 says to reassess the control programme, check treatment is working and resample. Above 1,000, or with persistent low-level positives, resample, shot-dose as a precaution, reassess the whole programme and resample again within 48 hours. A 'not detected' result doesn't mean there's no risk.
West London roots, towers looked after up and down the country.
We're based in Chiswick, West London, and most of our work is in London and the surrounding counties. We also look after sites across the rest of the UK, so if you manage plant in several regions, one contractor can cover the lot. Each area page below covers the local sites, water and access.
Talk to an engineer
- Phone
- 020 3633 6064
- Office
- The Lightbox G16, 111 Power Road
Chiswick, London W4 5PY - Coverage
- Nationwide, specialising in London & the Home Counties
Need a treatment contractor who explains things properly?
Tell us about your system and we'll come back with a clear, itemised quote. No hard sell, just a straight answer on what your site needs.