Tap Water Temperature

Anonymous

Mixer-taps my friend... they're the future - I've tested em!

Julian Wilkinson
Member - 43 posts

I believe that hot water should be stored at 60c, and supplied at outlets at a temperatute above 50c. Water at this temperature does not allow bacteria to grow. If mixer taps are used then they should not have a spray on the outlet particularly if they are seldom used, to avoid any possibility of exposure to legionella bacteria.

Outlets should be marked to warn users that the water is hot, and there should of course be a documented risk assessment relating to water systems together with a water hygiene log book recording temperature testing and maintenance detail of both hot and cold systems.

Philip Kenny
Member - 1 post

Hello Rupert

I have very briefly answered some of your questions

It should be ensured that hot water is stored within the HWS cylinder at equal to or greater than 60C and hot water services temperature at the outlets should achieve a temperature of at least 50C within one minute of flushing.

Temperatures exceeding 60C at the outlets pose a significant scalding risk. I suggest that the outlets are identified and clearly labelled ?Very Hot Water? using the appropriate signage in accordance with The Health and Safety (Safety Signs and Signals) Regulations; 1996.

You state that your hot water is currently too hot to use. I would therefore consider fitting mixer taps or thermostatic mixing valves as suggested by our Peter Kay & Pheonix Nights fan, Brian

It should be ensured that hot water supply to thermostatic mixing valves/taps is equal to or greater than 50C. Additionally, temperatures ranging between 38 ? 42C should be obtained to prevent scalding of users.

WRc/WRAS Approved Type 3 fail safe thermostatic mixing valves and taps are utilized to prevent scalding of users. (NHS Estates Specification D08 - refer to section 3.6)

I would suggest, that a full and detailed Legionella Risk assessment is carried out on your water plant and distribution systems. The RA will identifiy the sentinel outlets for monthly temperature profiles, asset all water related plant and a 2 dimensional schematic should be produced

Rupert Dingley
Member - 16 posts

Andrew

Thank you for your helpful comments.

My question did relate to our Legionella Assessment, which has recently been done, as I was concerned that whilst the water in the boilers were hot enough to prevent legionella, it is too hot when it comes out of the taps. Temperature was recorded as 62 degrees C at the taps

We already have signage in place, but it seems to be rather pointless having hot water if we can not actually use, as it is so hot.

Seems a mixer tap would be the solution.

Anonymous

The Thermostatic Mixing Valve Manufacturers Association produce info' Tel: - 0207 793 3008

The Heating and Ventilating Contractors Association produce the "Domestic Central Heating Installation Specification" this publication gives full details. Tel: - 01768 860405 for purchase.

Anonymous

Safe hot water is more than just a concern about Legionella, it must also address the risk of scalding. The Child Acident Prevetion Trust (CAPT) has been working with industry and legislators to develop guidance. The current guidance document, BRE IP 14/03, is available from www.safewater.com for free.

Anonymous

Our TM13 Minimising the risk of Legionnaires disease is the standard reference for designers. This also deals with maximum safe temperatures at the outlet. In general it agrees with what has already been said.

I cannot find anything in writing, but I believe thatr there are proposals to make mixer taps compulsory under the Building Regulations.

Jonathan David, CIBSE

Anonymous

I endorse previous comments regarding Legionella and the use of thermostaic mixer valves. The temperature at the taps should not exceed 43 degrees C.

I have concern about the use of warning labels and the DDA as it is assumed that the user can read them!

Anonymous

I'm a director of a company specialising in legionella control and can confirm the following:

Hot water calorifier temperatures must be maintained at 60°C or above throughout the entire vessel. Sometimes legionella bacteria proliferate in the lower section of a calorifier (i.e. below the heating elements) where the water can be less than 30°C even if water at the top of the unit is > 60°C. In this case the installation of a shunt pump is recommended. The Secondary flow temperature from the calorifier must exceed 60°C and the secondary return must exceed 50°C (if applicable) while all associated hot water outlet temperatures must be at least 50°C. However, there are some cases where this outlet temperature is not allowed such as hospitals and elderly care homes due to scalding. As a result, these premises must install thermostatic mixer valves and these should be adjusted to achieve an outlet temperature of 43°C. Cold water outlet temperatures must never exceed 20°C.

As a point of interest, legionella can not survive for long periods above 50°C and most will die within 2 minutes at 60°C.

The CIBSE TM13 was published some time ago and has really been superseded by the Health and Safety Commission's Approved Code of Practice (L8) which includes guidance on controlling legionella bacteria in water systems approved by the HSE.

You can find out more about our company at: www.amphibia.co.uk

Emit Brown
Member - 1 post

Note: remember to make provisions for recording hot water tap temperatures when fitting a thermostatic controlled mixer valve to sentinal taps.

Graham Kenyon
Member - 32 posts

It seems absolutely ludicrous that we should have to put up notices that say "Hot Water may be Hot". What a revalation !

Using arguments about children doesn't work either - because some children are too young to read the notices.

BUT

It should be an absolute requirement that places who have decided to remove plugs to prevent flooding of bathrooms, provide mixer taps - otherwise, no-one can safely use the "Hot Water" !!!!