Legionella Risk in Homes and Businesses: What Property Owners Need to Know

Legionella Risk in Homes and Businesses: What Property Owners Need to Know

Legionella is often associated with large buildings, hotels and healthcare premises, but the risk is not limited to these environments. Homeowners, landlords, commercial property owners and businesses with hot and cold water systems should understand how Legionella bacteria can develop and what practical measures can help control the risk.

Legionella bacteria are naturally present in water. The concern arises when conditions within a man-made water system allow the bacteria to multiply. Poor temperature control, stagnant water, scale, sludge, rust, organic matter and biofilms can all contribute to an environment where Legionella may grow.

For property owners and businesses, good water hygiene is therefore not simply about keeping water looking clean. It is about understanding how the entire water system operates and taking reasonable steps to control potential risks.

1. Understand why Legionella can become a problem

Legionella bacteria can multiply particularly well when water temperatures are between approximately 20°C and 45°C and nutrients are available within the system. Stagnant sections of pipework, poorly maintained storage tanks, scale and sediment can provide conditions that support bacterial growth.

This means a water system can appear perfectly normal while still requiring attention.

For example, a property may have:

• A hot water cylinder that is not operating at the appropriate temperature

• A cold water storage tank containing sediment or debris

• Long or unused sections of pipework

• Guest rooms, offices or bathrooms that are rarely used

• Showerheads that have accumulated scale

• Plumbing alterations that have created unused branches

• Poorly maintained thermostatic mixing valves

Identifying these conditions early can make water hygiene management considerably easier.

2. Keep hot water hot and cold water cold

Temperature control is one of the main strategies used to reduce Legionella risk in hot and cold water systems.

HSE guidance states that cold water should be maintained, where possible, below 20°C. Hot water should be stored at a minimum of 60°C and distributed so that it reaches at least 50°C within one minute at outlets.

These figures are important because simply checking whether water feels warm or cold is not enough.

A professional temperature check can identify whether the system is actually achieving the intended operating conditions. Where a building has a more complicated hot water system, checks may need to include storage temperatures, flow and return temperatures and selected sentinel outlets.

Property owners should also consider scalding risks. Higher hot water temperatures can present a serious hazard, particularly in properties occupied by children, older people or vulnerable individuals. Where a significant scalding risk exists, appropriate controls such as thermostatic mixing valves may need to be considered.

3. Do not overlook stagnant water

Water that remains unused for long periods can create additional challenges.

This is particularly relevant to:

• Empty rental properties

• Holiday lets

• Guest accommodation

• Commercial buildings with unused offices

• Vacant retail units

• Properties undergoing refurbishment

• Buildings with rarely used bathrooms

• Seasonal businesses

Infrequently used outlets should be incorporated into a suitable flushing programme. HSE guidance recommends regular flushing of infrequently used outlets, with weekly flushing commonly used as part of Legionella control where appropriate.

Flushing should be carried out safely and in a way that avoids unnecessary aerosol generation.

If a property has been empty for an extended period, do not simply assume that turning the taps back on resolves every water hygiene concern. The condition of the wider system should be considered.

4. Check tanks, cylinders and associated equipment

Water storage equipment needs routine inspection.

Cold water storage tanks can accumulate sediment, scale and other debris. Tanks should have suitable covers and should be maintained in a clean condition. HSE guidance recommends that cold water storage tanks are checked to ensure they remain clean, with inspection and remedial work undertaken where necessary.

Hot water cylinders and calorifiers can also develop deposits over time. Internal inspection, where practical, can help identify scale, sludge or other conditions that may affect the system.

Cleaning should not be treated as a one-off solution. The frequency of inspection and cleaning should reflect the condition and risk characteristics of the particular system.

5. Pay attention to showers and taps

Showers can create aerosols, which is one reason they deserve particular attention when managing Legionella risk.

Scale and contamination can build up inside showerheads and hoses, particularly where equipment is poorly maintained or infrequently used.

HSE guidance recommends dismantling, cleaning and descaling showerheads and associated equipment at appropriate intervals, commonly quarterly or as determined by the risk assessment.

Businesses and landlords should therefore avoid treating shower maintenance as purely cosmetic. It forms part of a wider water hygiene programme.

6. Plumbing alterations can change the risk

Renovations, extensions, new bathrooms and changes to commercial premises can significantly alter how water moves through a building.

New pipework can introduce:

• Dead legs

• Blind ends

• Long pipe runs

• Unused branches

• Poorly insulated sections

• Low-use outlets

• Areas where hot and cold pipes influence each other's temperatures

These issues can be difficult to identify once walls, ceilings or service areas have been closed up.

For larger projects, water hygiene should therefore be considered during the design and commissioning stages rather than left until the building is ready for occupation.

What should homeowners, landlords and businesses do?

Start by understanding your water system.

Identify whether the property has mains-fed water, cold water storage, hot water cylinders, calorifiers, circulating hot water systems, TMVs or other components that could influence water hygiene.

Next, establish whether there are areas of stagnation or outlets that are rarely used. Review the condition of tanks, cylinders, pipework, showerheads and other relevant equipment.

Where there is uncertainty, professional assessment can help determine whether the appropriate response involves temperature monitoring, tank cleaning, water testing, pipework disinfection, chlorination or other remedial measures.

The correct solution depends on the building, system design, occupancy, usage and findings of the assessment.

Water treatment support for properties and businesses

London Chlorination and Water Treatment provides professional water treatment and water hygiene services for homeowners, landlords, commercial property owners, businesses and property managers.

Support can include water testing and sampling, tank cleaning, chlorination services, pipework disinfection, Legionella risk assessments and hot and cold water system maintenance.

If you are concerned about the condition of your water system, have a property that has been vacant or are planning plumbing or refurbishment work, contact London Chlorination and Water Treatment to discuss your requirements and request a quote.