Step By Step Guide To Domestic Water Tank Cleaning and Disinfection

Water Tank Cleaning and Disinfection

Regular water tank cleaning and disinfection is essential to prevent the build-up of harmful bacteria and maintain a clean water supply. But can you do it at home?

The short answer is yes, domestic tank cleaning can be done at home.

However, you will need specialised chemicals, protective equipment, and knowledge on how to access your water tank safely.

This step-by-step guide shows you how to safely clean and disinfect your water tank at home, which products to use, and how often you should clean your tank.

Before we start, it’s important to understand why domestic water tank cleaning and disinfection is so important.

Why do you need to clean your water tank?

You must regularly clean your water tank to ensure good water hygiene and to prevent the spread of deadly bacteria like Legionella. Over time the water tank in your loft or basement will get dirty with sediment, scale, and debris.

You have a duty of care to those using your water tank. Vulnerable groups like children, the elderly or those with existing health conditions are particularly at risk from drinking contaminated water.

Dirty or poorly designed water tanks are breeding grounds for bacteria like Legionella, which if inhaled via water droplets, puts people at risk of catching Legionnaires’ disease.


Legionnaires’ disease is fatal in 10% of cases and can be avoided with regular water tank cleaning and disinfecting.


The elderly, children and those with underlying health conditions are particularly vulnerable. You have a duty of care to those using your water tank, therefore it must be cleaned and regularly maintained. This applies to both domestic and commercial water tanks.

Bear in mind that tank cleaning is an essential job even if you only use your supply for watering the garden. A hygienic tank means that the quality of your water and the lifespan of your tank will improve, as well as protecting the health of those using the water supply.

To ensure that your water tank is clean and fit for purpose it is essential to follow the correct tank cleaning procedures. This guide will provide an easy step by step to cleaning and maintain your water safely.


TIP: If you’re in doubt about your ability to properly clean your water tank it’s best to call an expert. Our expert team are trained in tight spaces, COSSH certified and only use industry standard cleaning products.


Water Tank Cleaning Equipment You’ll Need

Drinking water tank treatment requires the following specialised equipment:

  • Bleach
  • Mop
  • Gloves
  • Protective Glasses
  • Wet/Dry Vacuum
  • Water Delivery and Pumpout
  • Pressure Washer (optional)
  • Sump Pump (optional)

How To Clean and Disinfect Your Water Tank Step By Step

Step 1: Inspect your water tank

If you’re a landlord or letting agent you must first risk assess your water for Legionella. For guidance on how dirty a tank can get before Legionella is a problem read the Health & Safety Executive’s guidance.

A risk assessment will assess not only the quality of the water in your tank but also the design of the tank itself. For example, the lid should be tightly fitting and in good condition.

Our Landlords & Legionella Risk Assessment Guide provides up to date information on how to assess and test your water. WHO (The World Health Organisation) provide plans for drinking water tank treatment to help landlords regularly maintain their water tanks and the health of their tenants.

Step 2: Disinfect your tools

Before cleaning your water, it’s essential you clean your tools.

  • Mix 1 part bleach to 4 parts hot water in a clean bucket
  • Thoroughly clean all tools that will come into contact with the tank

Step 3: Drain your water tank

The first step is to drain your water tank. You’ll need 2-5 gallon pails of water for cleaning and rinsing.

  • Shut off the valve to the distribution line
  • Open the outlet valve or tap and drain out as much water as possible.
  • You can feed the hose to the garden and use the water to clean outside windows or wash the car to avoid wasting water

Step 4: Clean the inside of your water tank

Please do not carry out the following steps unless you are fully qualified to do so and are wearing the correct protective clothing.

  • Create a solution of 1 part bleach to 4 parts hot water and manually scrub the side of the tank to remove dirt and grime. You can use either a mop or pressure washer. Don’t forget to thoroughly clean any awkward corners or joints
  • Scrub any build-up that’s gathered on the bottom of the tank
  • Allow the mixture to sit for 2 hours
  • Use the wet/dry vacuum to remove the rinse water

Step 5: Wash & rinse your water tank

  • Rinse the tank with clean water
  • For best results use a pressure washer
  • Rinse until the water runs clear
  • Or, if you’re not using a pressure washer, fill the tank with hot water and allow to stand for a couple of hours before draining the water from the tank

For a range of water tank cleaning and maintenance equipment visit our premises in Perth where we have a comprehensive selection of products to assist with cleaning and disinfection, risk assessments and water testing.

Step 6: Water tank disinfection

  • Water tank disinfection is most effective when you use an anti-bacterial spray or add 5mL liquid bleach for every litre of water in the tank
  • Open the valve to the distribution line
  • Disinfect the water tank by running water out of all the taps in the distribution lines. Keep going until you can smell bleach in the water. This ensures the taps and pipes are thoroughly sterilised
  • Allow the bleach to sit in the tank overnight or for at least 4 hours

Step 7: Safely empty and dry your water tank

  • Run all of the taps until the tank is dry
  • Dispose of the disinfecting water (your water and sewer delivery service will be able to help)
  • Fill the tank with fresh water, allow to stand for 30 minutes and then flush the entire system again until you can’t smell bleach.
  • Tightly replace the tank lid properly to prevent any debris falling into your clean tank
  • Leave the tank for drying

Commercial tank cleaning

Like with domestic water tanks, commercial tank cleaning is vital in safeguarding against contaminants and preventing outbreaks of Legionnaire’s disease.

You must conduct regular inspections of your commercial water tank to determine that they are fit for purpose. Debris, mould, rust and corrosion can all pose a risk to human health.

Commercial water tank cleaning cost is dependent on the build and complexity of the tank, the premises on which it’s located and the water system involved. Landlords or those in charge of commercial premises have a legal responsibility to regularly risk assess their water tanks and maintain a regular tank cleaning schedule to safeguard public health. A professional company will provide you certification for your records in line with the L8 Approved Code of Practice & Guidance for the Control of Legionella.

pHX Water provide reliable and efficient domestic and commercial tank cleaning services in Scotland.

Water tank cleaning safety measures customers can expect:

  • Datasheets
  • A first aider on every visit
  • Detailed reports
  • Confined space trained specialists

We’ll send you COSHH data sheets before the visit and our engineers will arrive on-site with a copy. COSHH stands for Control of Substances Hazardous to Health. It is a law that states that employers must control substances that are hazardous to health and enforce preventative measures if needed.

Our safety measures also extend to confined space entry techniques. All of our engineers are trained in how to safely enter and manoeuvre around hot and cold water tanks and are supplied with specialist breathing equipment.

At the end of our visit you’ll be given certification and easy-to-understand safety information so that you know your water is safe and your business legally compliant. Call us today for a no obligation quote.

Water Tank Cleaning Frequently Asked Questions:

What is the best time of the year to clean my water tank?

It is recommended to clean the tank at the end of summer when there is usually very little water left.

How long will water tank cleaning take?

Experienced engineers will take 3-5 hours to clean a tank. However, the tank’s accessibility, dirtiness and the pipework will vary cleaning times.

How often should I clean my water tank?

We recommend tank cleaning once every six months.

How can I safely dispose of any liquid waste?

Do not discard liquid waste in rivers, ponds or natural water sources because the high concentration of chlorine will kill plants and fish. To safely dispose of liquid wastewater it should be transported via tanker to a sewage treatment plant. Alternatively, wastewater can be disposed of in a septic tank.

Can I clean my water tank at home?

Water tanks can be extremely hazardous due to the constricted space. Therefore, it’s important that you only enter a water tank if you are trained to enter confined spaces and know how to conduct water tank cleaning safely.

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