What Water Hygiene and Legionella Control Businesses Sell For in 2026

Updated August 2026 · refreshed quarterly. Next scheduled review: November 2026.

The UK water hygiene and legionella control market is experiencing intense consolidation. Driven by the non-negotiable statutory requirements of the Health and Safety at Work Act 1974, COSHH, and specifically the HSE's ACoP L8 and HSG274 guidance, the sector offers exactly what private equity and strategic acquirers want: mandated, recurring, non-discretionary compliance revenue. Premium regional leaders with £1M+ EBITDA are currently achieving 6.0x to 8.0x EV/EBITDA in competitive processes.

Over the past 24 months, major strategic moves have reshaped the landscape, including Mitie Group's £350M acquisition of Marlowe plc, alongside aggressive bolt-on activity from PE-backed platforms like Phenna Group, andwis, Complii, and Obsequio Group. This guide provides a data-driven framework for valuing UK water hygiene businesses, based on recent transaction evidence and sector multiples.

Contents

1. Why two businesses with the same EBITDA sell for very different multiples
2. The 2026 EBITDA Multiples Ladder
3. What kills the multiple
4. Worked examples
5. 2025 and 2026 transactions: United Kingdom
6. 2025 and 2026 transactions: United States
7. The buyer universe: who is acquiring in 2026
8. Demand drivers and regulatory calendar
9. Deal structure: how the consideration is paid
10. Public company multiples
11. FAQ
12. Methodology and sources
13. About DealFlowAgent
14. Related guides

Why two businesses with the same EBITDA sell for very different multiples

Two water hygiene businesses can report identical earnings and receive offers that differ by several turns of EBITDA. Buyers price the durability of the earnings, not the earnings themselves. The six factor groups below carry the weightings acquirers apply in practice.

Financial (22% weighting)

Deal process and buyer access (22% weighting)

Customer and revenue (16% weighting)

Operations (14% weighting)

People and organisation (13% weighting)

Strategic (13% weighting)

The 2026 EBITDA Multiples Ladder

Note: Multiples represent enterprise value to adjusted EBITDA. The lower bound represents an unprepared business sold without competitive tension. The upper bound represents a prepared business, professionally represented, in a competed process.

What kills the multiple

• Lacking LCA registration. Legionella Control Association registration is functionally close to a licence to bid on serious contracts. A target without it, or with a restricted category set, has a materially smaller addressable market. Buyers check the LCA register in diligence.
• Poor assessment-to-remedial pull-through. Risk assessment generates the remedial pipeline. A target with a large assessment book and no remedial capability is worth less than one that converts its own findings. Buyers model this pull-through rate in diligence.
• Outdated written schemes of control. A well-maintained written scheme with a current asset register creates switching friction. A target whose schemes are out of date has a retention problem it may not have priced.
• Public sector concentration risk. NHS trusts and local authorities dominate many books. While defensible, they are procurement-cycle exposed, price-competitive at retender, and slow-paying.
• Blending laboratory revenue. Laboratory analysis has different economics and different accreditation gates (UKAS 17025) than field service work. Blending them obscures the true margin profile.

Worked examples

Example 1: the discount profile (£800k EBITDA)

A water hygiene business generating £800k EBITDA, but heavily reliant on two FM contracts, using paper-based logbooks, and lacking full LCA registration.

• Base EBITDA: £800,000
• Applied multiple: 4.5x (lower end of the £500k to £1M band due to concentration and operational risk)
• Enterprise value: £3,600,000

Example 2: the premium profile (£800k EBITDA)

A water hygiene business generating the same £800k EBITDA, but with 75% recurring compliance revenue, full LCA registration, UKAS 17020, and proprietary compliance software.

• Base EBITDA: £800,000
• Applied multiple: 6.0x (upper end of the £500k to £1M band due to strong moats and recurring revenue)
• Enterprise value: £4,800,000

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2025 and 2026 transactions: United Kingdom

Note: the £350M Mitie acquisition was for the entire Marlowe group. Marlowe's Water & Air Hygiene segment reported £170M annual revenue. The implied EV/EBITDA for the whole group was approximately 10.7x to 11.2x.

2025 and 2026 transactions: United States

The buyer universe: who is acquiring in 2026

United Kingdom

• Mitie Group. Strategic (listed). Transformed the market with the £350M acquisition of Marlowe plc, bringing WCS Group in-house.
• Phenna Group. PE platform (Oakley Capital). Acquired Aquatech Environmental Services in September 2025.
• andwis Group. PE platform (H.I.G. Capital). Acquired IWS Water Hygiene in March 2026.
• Complii. PE platform (Ansor Capital). Acquired Sweetbriar Limited in July 2026.
• Obsequio Group. PE platform (Warren Equity Partners). Acquired Clear Flow Water Treatment in April 2026.

United States

• Solenis. PE platform (Platinum Equity). Completed the major NCH and Chem-Aqua transaction in November 2025.
• Ecolab and Nalco. Strategic (listed). Acquired Ovivo Electronics UPW in December 2025.
• ChemTreat. Part of Veralto (listed).

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Demand drivers and regulatory calendar

• ACoP L8 (4th edition, 2013). The approved code of practice for the control of legionella bacteria in water systems. The foundational document driving UK market demand.
• HSG274 Parts 1, 2 and 3. Technical guidance covering evaporative cooling, hot and cold water, and other risk systems.
• HTM 04-01. The NHS estates standard. Determines what a healthcare-weighted contract book actually requires.
• ASHRAE Standard 188-2021. Minimum legionellosis risk management requirements for US building water systems.
• CMS QSO-17-30. US federal Medicare requirement for healthcare facilities to have water management plans.
• 10 NYCRR Part 4. New York State regulation; the strictest state regime, requiring cooling tower registration and sampling.

Deal structure: how the consideration is paid

In the current market, smaller water hygiene bolt-ons (£500k to £1M EBITDA) typically see consideration structured as cash at completion, supplemented by deferred consideration or an earn-out over 12 to 24 months. These earn-outs are usually tied to revenue retention or EBITDA targets, protecting the acquirer against client flight.

For larger businesses (£1.5M+ EBITDA) acquired by PE-backed platforms such as Phenna or andwis, owners are frequently offered, or required, to roll over a portion of their equity into the acquiring platform. This aligns the owner's interests with the platform's growth and offers a second bite of the apple upon the platform's eventual exit. Working capital is typically settled on a completion accounts basis, though locked-box mechanisms are increasingly used for smaller deals to reduce post-completion friction.

Public company multiples

Note: public company multiples are sentiment markers only. There is no direct read-across from these global, diversified entities to private lower mid-market transactions.

• Veralto (NYSE: VLTO). Parent of ChemTreat. Water Quality segment reported approximately $3.3B revenue with 22.6% to 24.6% operating margins in 2025.
• Ecolab (NYSE: ECL). Water segment represents approximately 49% of revenue.
• Mitie Group (LSE: MTO). Facilities compliance group, now owner of Marlowe and WCS Group. Trades around 12x to 14x EV/EBITDA.

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Frequently asked questions

What is the average EBITDA multiple for a UK water hygiene business?

A typical established SME generating £500k to £1M EBITDA sells for between 4.5x and 6.0x EV/EBITDA. Regional leaders with £1M to £2.5M EBITDA command premium multiples of 6.0x to 8.0x.

How does LCA registration affect valuation?

Legionella Control Association registration is a critical value gate. Buyers view it as a licence to operate. Businesses with full registration across multiple categories command higher multiples because their addressable market is larger and more defensible.

Who are the main buyers of water hygiene companies?

The market is currently dominated by private equity-backed compliance platforms executing buy-and-build strategies. Key players include Phenna Group, andwis Group, Complii, and Obsequio Group, alongside strategic giants like Mitie.

Methodology and sources

This guide triangulates private market multiples using published TIC sector data (including Baker Tilly's 2026 TIC sector report and MAInsights platform data) and the implied ceiling established by Mitie's £350M acquisition of Marlowe plc. DealFlowAgent estimates are explicitly labelled. All transaction data is restricted to 2025 and 2026 announcements.

About DealFlowAgent

DealFlowAgent is a specialist sell-side M&A advisory firm. We protect the legacies of owner-led businesses in the building services and healthcare sectors. If you advise owners in the water hygiene or broader testing, inspection and compliance trades, we partner with solicitors and accountants to manage the M&A workstream. Visit our advisers page for details.

Related guides

• Fire Safety Valuation Guide
• HVAC Valuation Guide
• Electrical Contractor Valuation Guide
• Security Systems Valuation Guide
• Compliance, Testing & Inspection Valuation Guide

Disclaimer: this guide provides general market information and does not constitute financial or legal advice. Every business is unique, and valuations depend on specific operational and financial circumstances.

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