Cold Water Storage Tank Regulations 2023 – Everything You Need To Know

Many enquire about what the cold water storage regulations are in Ireland and unclear as to the size and type of water storage tank that is needed in either a new house or in a renovation. would like to tell you a bit more about what the cold water storage regulations are before you buy your new water tank to help you select the correct one.


What are the Main Regulations for Cold Water Tanks?

The Building Regulations Technical Guidance document G for Hygiene states that:

The cold water storage tank should have an actual capacity of not less than 212 litres in the case of a dwelling containing up to three bedrooms and an actual capacity of not less than 340 litres in the case of a dwelling containing four or more bedrooms.

The water tank should be properly covered but not airtight, accessible for cleaning and replacement, and fitted with an overflow pipe so located as to discharge in a manner that will give ready warning of the occurrence of overflow without causing any nuisance or any dampness in the dwelling.

The service pipe to each dwelling should be provided with a stopcock or sluice valve fitted with a crutch wheel for manual operation in a convenient position within the dwelling and near to the point of entry of the pipe to the dwelling.

The cold water tank, when located in the attic, has the top and sides of the tank insulated. The area underneath the cistern should be left uninsulated and continuity of tank and ceiling insulation should be ensured (see Diagram 3). Where raised tanks are used, to aid head pressure, the ceiling should be insulated as normal and all surfaces of the tank insulated separately. Provision should be made to ensure ventilation of the tank.


Many local councils now provide specific detailed guidelines as to what cold water storage should be provided in their county.

Each premises must be fitted with a cold water storage facility adequate and appropriate for the use of the premises and sized for a minimum for 24 hours normal usage. Water storage tanks must be of an approved type to protect the quality of stored water.

Guideline storage volumes for domestic and non-domestic buildings are shown below:

Building Use Minimum Cold Water Storage for new Developments using low flush and dual flush WCs
Dwelling House or Apartment up to 2 Bedrooms 225 Litres
Dwelling House or Apartment up to 3-4 Bedrooms 320 Litres
Dwelling House or Apartment over 4 Bedrooms 450 Litres
Hostels (with communal bathrooms) 90 Litres per head
Factory 45 litres per head of staff
Hospitals, maternity 455 Litres per bed
Hospitals, general 227 litres per bed
Hospital staff (non residential) 45 litres per head of staff
Hospital, nursing home & medical quarters 136 Litres per head
Hotels (bedroom with private bathrooms) 600 Litres per bedroom
Offices 45 Litres per head of staff
School, day, boys 23 Litres per head
School, day, girls 36 Litres per head
School, boarding 136 Litres per head
Restaurant and canteens 18 Litres per meal

Some of our approved water storage tanks

from €140.00 ex VAT
(€172.20 inc VAT)
from €185.00 ex VAT
(€227.55 inc VAT)

from €320.00 ex VAT
(€393.60 inc VAT)
from €250.00 ex VAT
(€307.50 inc VAT)

SureStop StopCocks that are suitable:

Special Offer
€160.26 from €150.00 ex VAT
(€184.50 inc VAT)
Special Offer
€66.30 from €61.00 ex VAT
(€75.03 inc VAT)

Special Offer
€35.78 from €30.00 ex VAT
(€36.90 inc VAT)

How Often Does My Cold Water Tank Need to be Cleaned?

While water tank cleaning and disinfection is not a legal requirement, no matter how well designed the cols water storage tanks are, there will always be a risk from contamination.  If contamination does get into the water tank and is allowed to build up over time, it will provide a breeding ground for legionella and other bacteria. Water tank cleaning and disinfection is therefore a necessity to prevent any contamination. 

We recommend that you inspect your tank once a year as often these cold water storage tanks become dirty with debris, sediment, limescale, sludge, fouling, mould, stagnation, rust and foreign bodies. Inspecting your water tank on a regular basis will flag up whether you need to clean out your tank.

Some checks to carry out while inspecting your tank are as follows:-

  • Cold water storage tanks must be placed in a cool place, with insulation provided if necessary. 
  • Stored cold water must be at a temperature of less than 20°C – check once a month by running the cold tap for a couple of minutes before taking the temperature. 
  • The temperature at the ball valve outlet needs to be checked every six months. 
  • The volume of water stored in the tank needs to be kept to one day’s usage. 
  • If you have more than one tank, link them together so water flows through all of them and there is no stagnation. 
  • Fit the storage tank with a tight-fitting lid and air vent to prevent dirt and contamination. 


What Other Water Tanks are Available on supply a large range of water tanks for various purposes that include rainwater harvesting tanks, large agricultural water tanks, garden tanks, potable water tanks, water butts, flexible bladder tanks, one piece insulated grp water tnaks and sectional water tanks.

To see our full range of water tanks click Water Tanks


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