Cold Water Tank | Cold Water Storage Tanks

Choose the right cold water tank and the right accessories the first time. Our range covers trusted Davant circular cisterns in popular sizes, insulated lagging jackets (40 mm and 80 mm “Super Snug”), lids, complete Byelaw-ready packs, ball valve kits, backing plates and fitting kits, everything you need to install or upgrade a loft or header tank with confidence. 

Types of Cold Water Tanks

There are five main types of cold water tanks to choose from: Loft Tanks, Rectangular tanks, Square tanks, Header tanks, and Coffin tanks. They differ in a few different ways, but for the most part, they all have the same general features.

Loft tanks

Loft tanks are any type of water loft tank that is installed in the roof space of a building.  Cold water Loft tanks are usually made from plastic, and they come in a wide range of different sizes. Loft storage is popular because it's cheap and easy to install.

Rectangular tanks

Rectangular tanks, as the name suggests, are shaped like a rectangle. They are also available in different sizes, ranging from small to large, but they take up more floor space than other types of storage.

Square tanks

A square tank is any water tank that has similar height and width measurements (such as 1200mm by 1200mm). They're also easy to install, and it's not difficult to add insulation or fit a tank cover.

Header tanks

The header tank is used to fill the heating system and accommodate the water expansion during the heating cycle. It features an overflow pipe that leads outside, a mains water supply connected via a ball valve to fill the system, a cold feed line and an open vent pipe

Coffin tanks

A Coffin tank, also known as a cold water coffin, is another type of cold water tank. The name comes from the shape - it looks like a coffin! Coffin tanks are usually around 2000mm long and 750mm wide.

Choosing the Right Cold Water Tank Size

If you're not replacing an existing cold water tank, the first thing to decide is how much cold storage you need. This will make sure you buy a size that's big enough for your needs. 

• For most people, this is between 30 and 100 litres of storage. If you've got small children or the elderly living with you, choose a larger tank - 100L can be enough for two adults' daily needs.
• For a family of three or four, you'll want a tank closer to 120-150L. If you have a larger family, the rule is 100L storage for each additional adult living in your house.
• Remember that these are only guidelines - if one person in the household has different showering needs (like bathing toddlers), then you'll need a bigger tank.

Once you know how much cold storage you need, take a look at our range to find a size that's right for your family!

Can you drink water from a cold water loft tank?

Cold water storage can be a safe way to store drinking water at home. However, the tank should have a good quality air gap valve fitted and be used monthly by flushing it out with supplied chemicals. Never drink from a cold water loft tank without ensuring that it has been thoroughly cleaned and flushed out with a non-bactericidal cleaner. A lid should also be secured to the tank, as bacteria can grow in water if left stagnant.

So, before you buy a cold water storage, make sure it's suitable for use with drinking water - check that it has all these features.

Cold water storage tanks are fitted with a fine mesh material below the tank's fill-point to catch any sediment or limescale which might be present in your incoming supply.

Should you buy a WRAS approved cold water Storage?

All water plumbing products sold in the UK must comply with the Water Regulations Advisory Scheme (WRAS) which means that they're safe to use.

You'll find WRAS approval on most products, but not all tanks will have it; you should check for this before buying to be sure.

There are different types of cold water storage tanks available – some have a tank inside an outer insulation shell, others have insulation wrapped around the outside. In both cases WRAS approval will make sure that there is no risk of the tank leaking

Keep your water storage tanks insulated

One important factor when choosing cold water storage for an unheated part of your homes is that it should have suitable insulation to keep the water as cool as possible.

A cold water storage tank that doesn't have any insulation is fine if you only use the hot water occasionally. However, if you're using it every day, or even a few times a week, then this kind of tank can be terribly inefficient and unnecessarily expensive.

If you are putting cold water storage in an unheated part of the house, then consider having the tank insulated on the outside with a proper insulation jacket. It will keep your tank cool even when there is no hot water being used in your property. This will keep the water cool for as long as possible, reducing heat loss by up to 65%.

Insulation jacket for water storage tanks comes in the form of rigid polyurethane foam insulation, either wrapped around the tank or fitted inside an outer casing. It's also available for small underground storage tanks.

Ideally, you should also wrap insulation around the control box and pipes that feed into the tank – all of these things contribute to heat loss and higher energy bills.

Cold water tanks maintenance and tools

A cold water tank typically requires yearly maintenance which involves pumping out the sediment that builds up in the tank over time. To do this, a removable inspection plate must be fitted to your hot water storage as well as an overflow pipe or similar.

However good practice dictates that:

• A cold water loft tank must have a lid that is tightly sealed and correctly fastened to prevent birds, rodents, and dust from entering the water.
• An overflow pipe must be fitted to a cold water tank to transfer excess water outdoors so that no flooding takes place.
• The cold water tank should be not too big so that the water is not left in it too long..
• A breather apparatus must be installed on top of the cold water tank. 

Benefits of a Cold Water Tank

• Reliable water supply – stores water ready for use even during periods of high demand.
• System protection – helps balance water pressure and supports traditional heating systems.
• Energy efficiency – when paired with insulated jackets, it reduces heat loss and protects against freezing in loft spaces.
• Hygiene and safety – secure lids and screened overflows help keep stored water clean and safe for domestic use.
• Compliance – Byelaw 30 kits ensure installation meets UK water regulations.

 Applications of Cold Water Tanks

• Domestic loft storage – providing water for bathrooms, showers, and toilets.
• Heating systems – feeding traditional boilers and serving as header tanks in central heating setups.
• Backup supply – ensuring water availability during temporary supply interruptions.

Guidance on the Selection of a Cold Water Tank

• Capacity needs – a 25-gallon tank is suitable for smaller households, while a 50-gallon tank is better for larger families or properties with higher demand.
• Insulation requirements – if your tank is in an unheated loft, opt for a 40 mm or 80 mm insulation jacket. The thicker the insulation, the better the protection.
• Compliance packs – choose a complete pack (with Byelaw 30 kit, lid, insulation jacket, and fittings) to save time and ensure everything is regulation-ready.
• Accessories – consider ball valve packs, fitting kits, and lids for easy maintenance and long-term reliability.

Installation Tips

• Fit securely – always use the correct backing plate and ensure the tank is properly supported.
• Use a screened lid and overflow – prevents contamination and keeps the water safe.
• Insulate fully – cover both the tank and connecting pipework to guard against freezing and heat loss.
• Check regularly – inspect ball valves, overflows, and the lid annually to ensure the system runs efficiently.
• Avoid oversizing – pick the right tank size to promote good water turnover and prevent stagnation.

Why Choose Build4Less?

• Trusted brands – we supply Davant cisterns and accessories designed for long service life.
• Complete solutions – from tanks to jackets, Byelaw 30 kits, and spares, everything is available in one place.
• Value for money – competitive pricing on quality tanks and accessories.
• Expert support – straightforward product guides and friendly advice help you make the right choice.

Fast UK delivery – so you can get your project moving without delay.

Frequently asked questions about Cold water tanks

• What is the cold water storage tank for?

A cold water tank holds the tap water from your household supply. This means when you turn on a hot or cold tap in your house, water travels from the tank to your appliances that need constant hot or cold running water, such as dishwashers and washing machines.

• How big cold water storage tank do I need?

The size of your cold water tank will depend on the number of people living in your household. The average family will only need a 100-150 litre cold water tank, but if you have several adults sharing one house, or lots of teenagers who take long showers, double the amount.

• What is an insulated cold water tank?

Insulated cold water tanks have an extra layer of insulation on the top and on some sides. This helps them retain heat more efficiently.

• How much does a cold water storage tank cost?

The price of a cold water tank varies depending on its size and the insulation involved. A basic 100 litre cold water storage tank will start from around £150, but it's best to check with your local plumber before buying one.

• Do I need a cold water tank with a combi boiler?

If you're planning to buy a combi boiler, you'll need to ensure that your cold water tank is fitted with an inlet pipe and an outlet pipe. These are usually included in the standard installation service when purchasing a new warm air or combination boiler.

• How do you install a cold water tank?

You can install a cold water tank yourself or contact your local plumber. If you'd like to try it yourself, be sure that you follow all the manufacturer's instructions carefully and check for any local building codes before starting work.

• How long does the water tanks last?

A well-maintained cold water tank in the UK should last around 15 years.

Conclusion

A cold water tank is a container that holds the tap water from your household supply.  Cold water tanks come in five different types: Loft Tanks, Rectangular Tanks, Square Tanks, Coffin Tanks, and Header Tanks. They differ in size and insulation type. The most common types are Loft tanks and Rectangular tanks.

Cold water tanks are a necessity for any home that has constant hot or cold running water. The type of tank you need will depend on the size and insulation level your household needs. Keep in mind that a well-maintained water storage tank should last around 15 years with proper care and maintenance!

If all of this sounds daunting and you want help making the best decision about which type of tank to buy, please contact us at Build4less. Our team would be happy to help with selecting or installing a new cold-water container for your house so that everything runs like a clock.