How to winterise a garden irrigation system

Illustration of drip irrigation beside vegetables in a raised bed

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As autumn temperatures drop, water left inside garden irrigation components can freeze and expand, cracking pipes, valves, sprinkler heads and timers. Winterising is not just about draining; it involves shutting off the supply, removing vulnerable parts, cleaning filters and storing everything where frost cannot reach. This guide explains the sequence and the checks that matter, based on manufacturer maintenance advice and RHS seasonal guidance.

Table of Contents

Shut off the water supply and drain the system

Start by closing the dedicated supply or isolation valve for the outdoor irrigation branch, following the installation instructions. If you cannot find a dedicated shut-off valve, trace the pipework back from the tap. Once the supply is off, open the end caps or drain valves on the irrigation lines to let water run out. For drip lines, open the end cap at the lowest point of the run. For sprinkler systems, open any drain valves fitted at low points. The RHS specifically advises draining standpipes and irrigation to avoid damage caused by water freezing inside them.

Do not assume that simply turning off the tap is enough. Water remains trapped in pipes, valves and fittings, and it is this trapped water that causes most frost damage. For a simple portable system, open a removable low-point connection only where the manufacturer permits it. Do not force sealed or permanent joints to create a drain. For complex installed systems, consult the installer or manufacturer’s winterisation instructions, because some systems may require compressed air to blow out residual water — a method not covered by the general advice here.

Detach and store water timers and controllers

Water timers and electronic controllers contain small internal passages, seals and sometimes batteries. Hozelock recommends detaching water timers, giving them a good clean and storing them in a frost-free place over winter. Leaving a timer connected to a tap or hose means any water inside can freeze and damage the valve mechanism or electronics.

Before storing, check the timer for leaks or perished O-rings and follow its battery-removal instructions for a long storage period. If a connector is dripping, the O-ring may have deteriorated; replacing it is a quick fix. Clean the timer body with a damp cloth, but do not immerse electronic parts unless the manufacturer says it is safe. Store the timer indoors, such as in a house or heated garage, where temperatures stay above freezing.

Drain hoses and hose-end tools

Detach all garden hoses from outdoor taps and drain them completely. For standard hoses, hold one end high and walk the length to push water out. For hoses with non-return valves or AquaStop fittings, the valves can prevent water from escaping. Hozelock advises attaching a hose-end accessory such as a spray gun or nozzle and leaving it in the open position so the water can fully drain. Without this step, water remains trapped behind the valve and can freeze.

Fabric-covered hoses, such as Hozelock Superhoze or Tuffhoze, need extra care. Dry them thoroughly before storage, and do not seal them in an airtight container, because trapped moisture can lead to mould. Washing with warm soapy water before storage helps remove dirt and residues. Coil hoses loosely without kinks and store them in a dry, frost-free place.

Hose-end tools — spray guns, lances, sprinklers, car brushes and multi-way tap adaptors — can retain small amounts of water internally. Bring them indoors to a warm place where any remaining water cannot freeze. Even a few millilitres of ice can crack plastic bodies or damage internal seals.

Clean and store sprinklers and drip emitters

Portable sprinklers that the manufacturer requires you to store frost-free should be taken indoors for winter, and this is a good opportunity to clean them. Many sprinklers have built-in filters that trap debris; if left dirty, the filter can clog and reduce performance next season. The exact filter location varies by model. For example, some Hozelock round sprinklers have a removable top that allows you to run water through the inside to clear the built-in filter. Other models have the filter inside the hose connection, with different release methods. Newer and older models can differ, so identify the exact sprinkler before opening it. Some rectangular sprinklers include a built-in cleaning tool to unblock the jets on the spray bar.

Do not assume one method works for all sprinklers. Check your sprinkler’s manual for filter access and cleaning instructions. Rinse filters under a running tap, clear any blocked jet holes with the provided tool or a soft brush, and allow everything to dry before storing. Drip emitters and micro-irrigation fittings should also be drained and cleaned. Open end caps, remove any small filters, and rinse them. If emitters are clogged, follow the manufacturer’s cleaning method rather than forcing a pin through, which can enlarge the hole and alter flow.

Protect outdoor taps and exposed pipework

Where the installation provides a dedicated internal isolating valve, close that branch and drain it as instructed. Insulate exposed pipework using a suitable outdoor arrangement; insulation slows heat loss but does not guarantee frost protection indefinitely. Pipe insulation or lagging can be fitted over exposed copper or plastic pipes. Pay particular attention to pipes running along external walls or through unheated spaces. Protect the tap and exposed pipework together. A tap cover alone leaves adjoining pipe vulnerable, and drainage requirements still depend on the installation.

Check that the insulation is dry and securely fixed, and replace any sections that are cracked or waterlogged, because wet insulation loses much of its effectiveness. This is also the time to check for leaks at the tap. If a connector drips, the O-ring may have perished; replacing it before winter prevents a small leak becoming a frozen blockage.

Check and replace O-rings and seals

Before storing any component, inspect the O-rings on connectors, hose ends, timers and sprinkler fittings. Rubber O-rings can perish over time or become damaged, leading to drips. Hozelock notes that replacing an O-ring is often a quick fix for a leaking connector. Remove the old ring and fit a new one of the correct size and material. This is a good time to order spare O-rings and seals so you have them ready for spring.

Do not use petroleum-based grease on rubber O-rings unless the manufacturer specifies it, because some greases can degrade the rubber. Use only the lubricant, if any, specified for the exact seal and fitting. Check the manufacturer’s guidance for your specific fittings.

Store everything frost-free

Hose reels, carts and auto reels should be washed down and checked for wear before storage. If the reel is wall-mounted, remove it if required and put it in a frost-free place. A shed or garage may not be frost-free; unheated outbuildings can still drop below 0 °C during a hard frost. Choose a location you know remains above freezing. An insulated box in an unheated shed cannot guarantee frost-free conditions indefinitely. The key requirement is that the storage area stays above freezing at all times.

Store sprinklers, timers, spray guns and other small parts in a labelled box so they are easy to find in spring. Keep hoses coiled loosely, not tightly wound, to avoid kinks. Fabric-covered hoses should be completely dry and stored with ventilation, not sealed in plastic bags.

Common mistakes and practical limitations

Forgetting to open end caps: water remains trapped in the line and can split fittings when it freezes.
Leaving timers connected: internal water freezes and damages the valve or electronics.
Storing fabric hoses damp or airtight: this encourages mould growth.
Assuming a shed is frost-free: many unheated sheds freeze; check the actual temperature on a cold night.
Not cleaning filters before storage: debris hardens over winter and blocks flow next season.

Not all irrigation systems have drain valves or removable end caps. If your system lacks an accessible drain, obtain its winterisation instructions before taking fittings apart. For large or permanently installed systems, consult the installer or manufacturer, because some require compressed air to clear water from buried lines. The advice here covers typical garden-scale hose, drip and sprinkler systems, not agricultural or commercial installations.

Useful products for this job

The links below open Amazon UK product searches. Check the exact item, seller, current price and compatibility before buying.

Pipe insulation or lagging for outdoor pipework: Suitable insulation slows heat loss from exposed pipes; it complements the installation’s winter drain-down procedure. Measure the outside diameter of your pipe and choose insulation with a matching internal diameter; check UV resistance if exposed to sunlight. Search Amazon for Pipe insulation or lagging for outdoor pipework.
Hose end spray gun or nozzle with open position: A compatible existing spray gun or nozzle can hold an AquaStop connector open while draining; check whether your hose instructions call for this arrangement. Confirm the connector type matches your hose fittings (e.g., Hozelock, Gardena) and that the trigger can be locked in an open position. Search Amazon for Hose end spray gun or nozzle with open position.
Replacement O-ring kit for garden hose connectors: Perished O-rings cause leaks; replacing them before winter storage prevents drips and frozen blockages. Check the size and material of your existing O-rings; some fittings use metric sizes, others imperial, and rubber compounds vary. Search Amazon for Replacement O-ring kit for garden hose connectors.

Related garden guides

Sources and further guidance

Guidance researched in September 2026. The feature image is an AI-generated illustration. Product guidance is based on published information, not hands-on testing.