Like all living organisms, Legionella bacteria need the right conditions to survive. Legionella control measures are largely aimed at ensuring that these conditions are not allowed to occur, thus effectively stopping the bacteria from flourishing in your water system. Identifying and removing potential sources of food for the bacteria is one such measure, but what form does this ‘food’ take?

Rust

Rust is one of the most common forms of nutrients for Legionella found in a domestic water system. Whether it’s in the pipework, water tanks or even the taps, where there’s water and oxygen you’re likely to have rust forming. Its chemical name is iron oxide and it forms on iron and steel when they come into contact with water and oxygen (the air in our atmosphere is 21% oxygen). Not only does rust act as food for Legionella bacteria but it also ‘eats’ the surface of the metal over time so causes weakening in the pipework and tanks, which increases the risk of flooding or water damage to your property.

It is possible to use a chemical corrosion proofer to help prevent rust. Ideally this should be used when the water system is installed, but it can be effective when put through existing plumbing.

If you find early signs of rust, use a wire brush to remove the rust then wash the area thoroughly. However, in more advanced cases of rusting your only option is to remove the affected pipework and replace it. Make sure that the fitter leaves everything clean and free of any metal particles or metallic dust as if they are left in your system they will encourage rust to form again quickly.

Biofilm

Biofilm is a layer of microorganisms that stick to each other to form a skin, typically on hard surfaces (such as pipes and tanks) but also on the top of any stored or stagnant water. The biofilm helps to protect any bacteria underneath the skin and biofilm can be very hard to remove, so it acts as an effective armour for Legionella. There are three things that must be present for biofilm to occur: moisture, bacteria and a surface, so you can see that a domestic water system is the perfect environment for it to form.

Biofilm can be removed by scrubbing and chemical treatment. Check if your water storage tank has a biofilm build-up and then either follow our guide to cleaning it or call in the professionals (this is a service we offer too).

Sediment or debris

Sometimes you get a build-up of sediment in plumbing systems and if you have a water tank without a well-fitting lid you may also find that debris can get in and clog things up. Such particles are another food source for bacteria so you need to take measures to prevent build-up or get rid of it. Flushing the system is usually an effective way to keep water flowing but in more extreme cases you’d be advised to call in a plumber to track down and expel any sludge or sediment.

As with all forms of Legionella control, by assessing your water system thoroughly and identifying and rectifying any issues promptly, you’ll be able to keep potential sources of Legionella nutrients to a minimum and ensure a safe and healthy environment for your tenants.