Domakihub How to Fit a Flow Restrictor to a Tap: Save Water and Cut Bills
A simple DIY upgrade that cuts household water waste without a plumber.
Reviewed by Domakihub home & decor pros · 2026-06-23 · 4 min read
Fitting a flow restrictor to a tap is one of the fastest, cheapest ways to reduce water consumption in a Greek home, holiday rental, or hotel — where water bills and summer pressure drops both bite hard. The video above walks through the physical installation, and the guide below gives you the full context: what to buy, how to size it, and exactly how to fit it without specialist tools. No licensed plumber is required for this job; it is a straightforward DIY task on the cold- and hot-water supply outlets inside the property.
What Is a Flow Restrictor and Why Bother?
A flow restrictor is a small disc or insert — often made of rubber, silicone, or hard plastic — that sits inside the aerator housing at the tip of a tap spout. It reduces the maximum volume of water that can pass per minute without noticeably affecting the sensation of pressure, because most restrictors are paired with an aerator mesh that mixes air into the stream.
In Greece, municipal water pressure varies dramatically between urban centres and island or rural networks. A restrictor rated at 5–6 litres per minute (l/min) is typically comfortable for handwashing and light kitchen use, while 8 l/min suits a busier kitchen. Without any restrictor, a standard household tap can push 12–20 l/min — most of which goes straight down the drain.
What to Buy: Choosing the Right Restrictor
Most modern taps use an M22 (22 mm external thread) or M24 (24 mm) aerator housing. Before buying anything, unscrew the existing aerator from your tap spout — it threads off counter-clockwise by hand or with a coin — and check the thread diameter with a ruler or bring the old insert to a hardware shop. Restrictor discs are sold as standalone inserts or bundled with replacement aerator assemblies; either works.
For rental properties and hotels aiming for water-efficiency certification, choose a WaterMark- or WRAS-approved restrictor at 4–6 l/min. For a home kitchen where you fill pots regularly, 8 l/min is the more practical choice. Always buy a brand that states a specific flow rate on the packaging rather than a generic 'water-saver' label.
How to Fit a Flow Restrictor: Step-by-Step
- 1
Turn off the water and clear the spout
There is no need to isolate the mains supply for this job — you are working at the tip of the tap, not on the supply pipes. Simply turn the tap handle to the off position. Open the tap briefly to release any residual pressure in the spout, then place a small cloth or towel in the basin to catch the aerator housing and any small parts.
- 2
Unscrew and disassemble the existing aerator
Grip the aerator housing at the end of the spout and rotate it counter-clockwise. Most unscrew by hand; if it is stiff from limescale, wrap the jaws of a pair of pliers with masking tape and use gentle, even pressure. Once removed, tip out the internal stack: typically a rubber washer, one or two mesh screens, and a flow disc (which may already be present). Note the order of the parts — a phone photograph is useful here.
- 3
Insert the flow restrictor disc
Take the new restrictor disc and seat it at the inlet end of the aerator housing — the end that screws onto the tap. The disc usually has a small central hole or star-shaped opening; this faces up toward the water supply. Layer the mesh screens back on top in the same order as before, then fit the rubber washer last. If your new aerator kit comes as a pre-assembled cartridge, simply drop the cartridge into the housing as a single unit.
- 4
Refit the aerator and check for leaks
Thread the aerator housing back onto the tap spout clockwise by hand until snug. Do not over-tighten with pliers — hand-tight plus a quarter turn is sufficient, and the rubber washer does the sealing. Turn the tap on slowly and watch the joint between the housing and the spout for any drips. If you see a slow drip, tighten slightly or re-seat the washer.
- 5
Test the flow rate and adjust if needed
Hold a one-litre jug under the tap and time how long it takes to fill with the tap fully open. Divide 60 by the number of seconds: for example, 10 seconds to fill one litre equals 6 l/min. If the result is still above your target, swap to a disc with a smaller orifice. If the flow feels uncomfortably weak for your use case, move up one size. Many hardware suppliers and online plumbing shops sell multi-pack assortments of restrictor discs (2, 4, 6, 8 l/min) for this reason.
Rather have a pro handle it?
Get a vetted plumbing pro in your city — one number, booked in EN/EL/DE.
FAQ
- Will a flow restrictor noticeably reduce water pressure at the tap?
- A well-chosen restrictor paired with an aerating mesh should feel similar to an unrestricted tap because the aerator mixes air into the stream to maintain perceived pressure. You may notice slower pot-filling in the kitchen, which is why 8 l/min is the common compromise for kitchen taps and 5–6 l/min for bathroom basins.
- Do I need a plumber to fit a flow restrictor?
- No. Fitting a flow restrictor is a DIY job that requires no tools beyond your hands and optionally a cloth-wrapped pair of pliers. It involves no supply pipe connections, no soldering, and no work on mains pressure systems. Greek building regulations do not require a licensed plumber for aerator-level tap maintenance.
- My tap's aerator is badly caked with limescale — what should I do?
- Soak the aerator housing in undiluted white vinegar for 30–60 minutes before attempting to unscrew it. Greek mains water is typically hard, especially on islands, so limescale buildup on aerators is common. If the housing is corroded beyond recovery, replacement aerator assemblies (including a new restrictor disc) cost under five euros and are available in most hardware shops.