Water butts and garden watering: butts, hoses, simple irrigation and backflow

There are two ways to get water to a garden. You can collect rain off the roof in a water butt, or you can run water from the mains through an outside tap. Both are simple, but they are not interchangeable. Rainwater must never find its way back into the drinking water pipes, and anything connected to an outside tap needs protecting against water flowing backwards into the supply.

Water butts

A water butt is a plastic tank that collects rain from a downpipe. Most are fed by a rain diverter: a fitting cut into the downpipe that sends water sideways through a short hose into the butt. When the butt is full, a good diverter lets the water carry on down the pipe to the drain instead of overflowing.

Things that make a butt work well:

• Stand it on a firm, level base or stand. A full butt is very heavy. A stand also raises the tap high enough to fit a watering can underneath.
• Match the diverter to the downpipe. Round and square downpipes come in different sizes, so check yours before you buy.
• Fit the diverter at the right height. It needs to sit at or just above the top of the butt so the butt can fill, and so the diverter can send water down the pipe once it is full.
• Keep the lid on. It keeps out leaves, light and insects, and it matters for children's safety. Fit a lid that locks or clips if small children use the garden.
• Clean it out now and then. Sediment and leaves collect at the bottom.
• Think about winter. Water left in a butt and its tap can freeze. Many people drain the butt down or disconnect the diverter in a hard winter.

A water butt is for the garden. It should not be connected to any household plumbing. If you want to use rainwater inside the house, that is a proper system with specific rules, which our guide to rainwater harvesting explains.

Watering from an outside tap

The outside tap itself is covered in our frost-free outdoor tap guide, including where the double check valve should go. This section is about what you connect to it.

Hoses and reels. A hose on a reel with click-on connectors is the simplest setup. Turn the tap off when you finish, rather than leaving the hose under pressure all day with the gun shut.

Sprinklers and timers. A battery tap timer between the tap and the hose can run a sprinkler for a set time. It is a convenience, not a safety device.

Drip and soaker systems. Low-flow kits, with a main line and small drippers or a porous soaker hose, put water at the roots. Many plug into a hose connector.

Backflow: the part people miss

When mains pressure drops, for example during a burst main or when the supply is turned off for work, water can be drawn backwards. A hose lying in a pond, a bucket of soapy water or a weedkiller sprayer can then siphon dirty water into the pipes that feed your kitchen tap.

Water Regs UK's guidance on hose union taps says hoses used only for watering a domestic garden or washing personal vehicles "are typically categorised as a fluid category 3 risk which may be protected by the installation of a double check valve". It also says that a flow control device "is not a recognised form of backflow protection", so a tap timer or a trigger gun does not count.

The same guidance goes further for irrigation systems supplied from a hose union tap. It says "The installation of an irrigation system must be notified, conditions are likely to apply", and that irrigation pipework should be marked in line with BS 1710.

In practice:

• A simple hose or sprinkler on a properly protected outside tap is the common, everyday case.
• A permanent irrigation system, with buried pipe and zones, is a different thing. Talk to your water company before installing one, and expect them to set conditions.
• Do not leave the end of a hose in a pond, water butt, paddling pool or chemical container.
• Do not connect a hose from the mains into a water butt or rainwater tank to top it up through a submerged pipe.

These rules are the Water Supply (Water Fittings) Regulations 1999 in England and Wales. Scotland and Northern Ireland have their own water fittings rules, so check with your supplier there. We have not set out exactly what your setup needs; your water company or a WaterSafe plumber can tell you.

Products at Wickes

We haven't tested these. They are examples, with what the retailer's page says.

We haven't tested this. Figures are as the maker states them (checked 13 November 2026).

Is it safe to drink water from a water butt?

No. Water from a roof picks up dirt, droppings and debris. Use it for the garden only, and keep the lid on.

Does a tap timer count as backflow protection?

No. Water Regs UK says a flow control device is not a recognised form of backflow protection. The protection comes from a suitable check valve or arrangement on the supply.

Do I have to tell the water company about a garden irrigation system?

Water Regs UK guidance says the installation of an irrigation system supplied from a hose union tap must be notified, and that conditions are likely to apply. Ask your water company before you install one.