Water Butt Questions and Answers

All you probably didn't want to know about water butts, or water barrels as they are called in some countries. Although it is somewhat maddening to have to say, you should check your local regulations as to whether a water butt is permitted *.

What are water butts?

A water butt is a tank, often plastic, which is connected to a downpipe from a roof. It collects rainwater via a diverter which if installed correctly, will fill the water butt to the top. Once the water has filled the butt, any excess should continue down the drainpipe rather than overflow.

Their use in gardens has increased in popularity again, with them being relatively common previously before fading out. They have also become much cheaper over the last few years and may be purchased from most DIY and hardware stores. The cheapest and traditional water butts were constructed of plastic, usually green, black or blue in colour, however now there are some designer varieties available that give appearances of other more attractive objects such as wooden barrels, stone columns or terracotta containers rather than the utilitarian plastic. The designer varieties are typically more expensive, but in some cases can be made a feature of a garden.

What size water butt should I install?

The smallest size which can be bought is typically one hundred litres and will fill fairly rapidly on a smaller roof in heavy rainfall. They also are suitable for small gardens with space constraints. The standard size butt is around two hundred litres and is recommended for a standard house roof. If attaching to a large roof, bigger butts and tanks are available however care must be taken to ensure that the ground beneath large tanks can take the weight – which can be as much as a car when full.

Where should I position a water butt?

The obvious answer is next to a downpipe where the water butt can efficiently collect as much water as possible. Ideally, it should be affixed to a roof with a large collecting area – more roof space means water is collected quicker. Smaller roofs or conservatories or garages also work well. Some suggestions also attach water butts to sheds or greenhouses, however these have smaller collecting surfaces which mean that more rainfall is required to fill up even the smallest of butts.

Wherever you decide to install the water butt, the ground must be level and firm as an uneven butt may not fill correctly, could overflow, and could even tip over.

How should I link multiple butts together?

There are two ways to connect water butts, and will depend on usage and access.


This is where the pipe linking the two butts together is place at the top of the water butt. When connected to the downpipe, one butt will fill and then will overflow into the second. This allows the butts to also be drained independently, and if required, one butt can be removed for cleaning at a time. Most people will probably prefer the water butts to be connected together at the top.


This is the connection of the link pipe at the bottom of the butt. Both butts are filled evenly from the downpipe, and emptied evenly. The negative of this connection type however is that a butt can not be removed without draining (or blocking the connecting pipe) the other. Bottom connecting is preferable for use in locations where one of the butts may not be accessible for filling a watering can (such as down the side of a house or garage).

Can I connect a hosepipe to a water butt?

Not directly, as the water butt will almost certainly not have enough output pressure. However there are water butt pumps available which can be submerged into the butt and are able to pump water from the butt through the hosepipe. Also, some pressure washers can be connected to water butts, however larger capacities are preferable in this case due to how much water a pressure washer will use during operation.

Should I drain my water butt in winter?

It may be preferable depending on your location and the exposure of the water butt to the elements. In freezing weather, there is potential for the water to freeze, and in doing so, it may expand enough to split the butt. Damage can also be caused to the tap, diverter, and any linking pipes which have water in them if they are allowed to freeze.

If the butt is likely to freeze, it is recommended to drain it prior to any freezing conditions, and refill after the chance of heavy frost has passed in spring.

Also remember to disconnect the diverter to prevent the butts refilling. This can be done by putting a cap or bung on the pipe or ensuring that the diverter pipe exit is held higher than the its own overflow, which will ensure that water continues on down the drainpipe.

An alternative to draining which may have limited success depending on the conditions, is to place something buoyant in the water such as a tennis ball which can reduce the chance of ice forming. This will almost certainly only work in slightly freezing conditions.

Can I direct the downpipe straight into the water butt?

Many water butt lids have a cut-out for a downpipe to go through so this is an option if required. This is useful when there is no drainage in place, and so a diverter would be of little use. It should be noted however that once the butt is full, it will continue to overflow unless some other modifications are made to deal with the overflow.

Drainage issues can cause problems around foundations of buildings, so diverting the downpipe directly into the butt is not recommended if drainage is already in place.

How much will a water butt cost / save?

This costing works on the basis of a 100L water butt which currently can be found for £20. I live in Yorkshire and the current price per cubic metre (1000L) is 134.8p (excluding sewerage charges). A watering can is around 10L.

Taking the £20 cost and dividing by 134.8p gives us fifteen water butts worth of water (or 150 watering cans) for the payback. Everything else after that is saving money. Assuming the water butt is emptied and refilled fifteen times a year (which depends on usage), the water butt could easily pay for itself within a year and will be expected to last at least ten years – probably longer.

If the sewerage costs are included (which for Yorkshire are 95%) of the cubic metre price, the time to pay back the water butt effectively halves.

How often should I clean out a water butt?

Once a year is recommended. Debris from roofs along with insects and other matter are collected in the bottom of the butt, and eventually will cause smells. This is especially the case when running the downpipe directly into the butt rather than using a diverter.

Also remember to clean out a rain diverter to ensure that the maximum amount of water is being discharged into the water butt, as opposed to being lost down the drain.

Smells can be reduced by adding chemicals, however a clean once a year will suffice in most cases.

What other designs are available?

As mentioned previously, the various styles such as wood or stone are available. There are multi-tiered plastic butts which also double as planters – watering the plants as the butt fills. Wall attached butts are sold, though they tend to be up to 150L due to the weight when full. Barrels such as those used for whisky are also sold.

For larger requirements, tanks are available though they tend to cost several hundred pounds. These are useful in situations where a water butt pump would be used along with a hosepipe.

Could I make my own water butt?

Almost certainly. The taps, diverters and linking kits are generally sold separately. A butt could be made out of a barrel, old oil drum, or waste bin if needed. It would also be possible to make a custom frame and use a pond liner inside to store the water, however care would be needed to ensure the frame could take the weight of the water contained within a full barrel. A stand would also be required, so the design would need to take account of lifting the butt at least forty-five centimetres from the ground, and the stand would also need to be designed to take the weight.

Do you have any other suggestions?

When installing the water butt, and during maintenance, ensure that the guttering is in good condition and that the maximum amount of water is being collected. Take particular care to clean the gutter of debris, and ensure that all gutters flow correctly and do not leak.

* Am I allowed to install a water butt?

Surprisingly, this is not a stupid question and does not have a straightforward answer for everyone which means that it may be required to check your local laws. In the UK, yes, you are allowed to install a water butt without any form of governmental or council permission (landlord permission not withstanding). Larger storage tanks however may need authorisation and planning permission.

However, in America, the situation differs by state. Of particular note is Colorado where the situation until recently was that water butts were not permitted effectively due to the water rights having been purchased, and a water butt being seen as interfering with those. Other states have some restrictions in the capacity amount which may be collected.