Domakihub How to Clear an Airlock in a Water Pipe (Fast Fix)
Restore full water flow in minutes with these proven DIY methods.
Reviewed by Domakihub home & decor pros · 2026-06-23 · 4 min read
An airlock forms when a pocket of trapped air blocks water flow in your hot or cold water pipes — a common frustration in Greek homes, holiday rentals, and hotels after maintenance work, a mains supply cut, or a pump restart. The video above walks through the most effective removal techniques, and the step-by-step guide below gives you the exact process to follow in your own property. Most airlocks clear in under fifteen minutes without calling a plumber.
What Causes an Airlock?
Air gets trapped in your plumbing when the system loses pressure or runs dry — for example after the mains supply is cut and restored, after draining pipes for a repair, or when a pump runs without water and pulls air into the line. Holiday properties that sit empty are especially prone to this because the water has been off for weeks and the system is refilled quickly.
The trapped air sits at the highest point of the pipe and acts like a plug, preventing water from reaching a tap or shower. You will usually notice either a complete loss of flow or a sputtering, gurgling stream — often only on the hot side if the cold-water tank refilled normally but the hot circuit is still airlocked.
Before You Start: What You Need to Know
Identify whether your property has a gravity-fed system (cold-water storage tank in the loft or roof space feeding the hot cylinder) or a combi-boiler / pressurised system. The linking-tap method described below works best on gravity-fed systems. Pressurised combi systems are sometimes cleared simply by bleeding radiators or re-pressurising the boiler. Check your system type before choosing a method.
Turn off any electric immersion heaters or boilers before you work on the pipes. Water and live heating elements are a serious hazard. Make sure the mains cold supply is flowing properly to at least one tap before attempting any fix — if the whole building has no water, the issue is with the supply, not an airlock.
How to Clear a Water Pipe Airlock
- 1
Confirm the airlock location
Open every cold tap in the property one by one. Cold taps fed directly from the mains should run normally. If a hot tap sputters or gives nothing while the cold side works fine, the airlock is in the hot circuit. If both sides are weak on a particular floor, the airlock may be in a shared branch pipe. Noting exactly which outlets are affected tells you which section of pipe to target.
- 2
Try the linking-tap (hose) method first
This is the fastest fix for gravity-fed systems. Connect a short garden hose or washing-machine hose between the affected hot tap and a working cold tap nearby — ideally at the same sink. Turn on the hot tap fully, then the cold tap fully. The mains cold pressure will push back up through the hot line and dislodge the trapped air. Hold this position for 30 to 60 seconds, then release the cold tap first, the hot tap second. Try the hot tap normally; repeat once or twice if flow has not fully returned.
- 3
Bleed air from the highest fixture
If the hose method is not possible, go to the highest hot-water outlet in the building — usually a shower or basin on the top floor. Open that tap slowly and leave it open for two to three minutes. As water pressure gradually pushes the air bubble along and out, you will hear a hissing or gurgling sound followed by a burst of spluttering water and then steady flow. Keep a towel handy; the first surge can be vigorous.
- 4
Check and bleed any inline valves or air vents
Many plumbing systems have manual air vents (bleed points) fitted near the hot-water cylinder or at the top of the pipe run. Locate these small brass or plastic valves — they look similar to a radiator bleed valve — and use a flat-head screwdriver or bleed key to open them just a quarter turn. Hold a cloth underneath. You will hear air hissing out; close the valve the moment water appears. This directly vents the trapped pocket without any special equipment.
- 5
Restore and test all outlets
Once flow returns to the previously blocked tap, systematically open every hot outlet in the property from the top floor down and let each run for 30 seconds. This purges any remaining small air pockets that could re-form into a blockage. Finish by checking the cold-water tank level (if present) is refilling correctly and that the boiler or immersion heater pressure gauge reads within the normal range (typically 1 to 1.5 bar for a pressurised system). If strong flow has not returned after repeating these steps, the blockage may be a partial pipe scale build-up or a faulty valve — at that point, call a licensed plumber.
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FAQ
- Why does the airlock keep coming back?
- Recurring airlocks usually point to a deeper problem: a pump that is undersized and regularly draws air, a check valve that has failed and lets air back in when the system loses pressure, or a cold-water tank that empties faster than it refills. Fix the root cause — replace the faulty component or adjust the tank float valve — rather than repeatedly clearing the airlock manually.
- Can an airlock damage my boiler or hot-water cylinder?
- Yes. If an airlock prevents water from circulating through a boiler or electric immersion heater, the element or heat exchanger can overheat and burn out. Always switch off any heating appliance before working on the plumbing, and do not switch it back on until confirmed water flow is restored.
- Is this a job I can do myself or do I need a plumber?
- The linking-tap and bleeding methods are straightforward DIY tasks that require no special tools or qualifications. Most homeowners in Greece can clear a simple airlock in one attempt. You should call a licensed plumber if the airlock returns within days, if you have no working cold-water tap to use as a pressure source, or if the property has an older sealed heating system where the pressure relief valve may need attention.