The water inlet node in a flat
The whole thing, as a live schematic
This is not a picture but a schematic built in our editor from catalogue parts, and it passes the same compatibility checks the app runs — pan it, turn it, switch to 3D, open the parts list. If it holds together here, the parts mate by thread and diameter, and the parts list is counted from the same schematic.
The riser comes in at the top left; from it the cold and hot lines each run through their own inlet valve, strainer, meter and check valve, and only then branch out to the fixtures.
The order, and the reason for each part
Read the table as a chain: the reason column is why the part is there at all. A part that cannot name its reason does not belong in the node — it is money, pressure loss and one more thing that can leak.
| # | Part | Why it is there |
|---|---|---|
| 1 | Inlet ball valve, one per riser | Nothing below can be removed without it. Turn it every few months or it seizes and will not close on the day you need it |
| 2 | Strainer, 300–500 µm | Grit and scale from an old riser jam the meter impeller — the classic cause of meter failure |
| 3 | Water meter | Metering, by contract. After the strainer, before the first branch — that is what the rules require and what protects it |
| 4 | Check valve | In new buildings a code requirement, elsewhere the utility's; it also stops hot water crossing into the cold line through a mixer |
| 5 | Pressure reducer + gauge after it | Only if you measured over 5 bar. The gauge goes after the reducer: it is there to show what the reducer is set to |
| 6 | Fine filter | By the water and by what you own — not by default |
| 7 | Manifold or tees | From three or four fixtures a manifold pays for itself: any one of them shuts off alone |
| 8 | Valve on every branch | So one fixture can be worked on without turning the flat off |
Hot and cold each get the full chain. A shared strainer or a single check valve for both lines is a saving that ends with the hot line pushing into the cold one.
What people fit that does not need fitting
This is the half of the node worth arguing about. Each of these is common, and each one is either useless or actively harmful.
Where your responsibility begins
The line runs at the first shut-off valve: the riser and the valve on it belong to the building, and a leak there is a call to the emergency service, not a job for your wrench.
The meter is sealed, and no connection may be made upstream of the seal. Every branch, including the one to the washing machine, starts after it — a tee cut in before the meter is a metering offence, not a clever shortcut.
Manifold or tees
Both are acceptable. A tee layout uses less pipe and less space, but the fixtures share a line: run the washing machine and the shower goes cool. A manifold gives every fixture its own pipe from one point, so pressure holds and any branch can be isolated.
The rule that settles it is not comfort but the wall: a buried layout should have no joints in the screed, and only a manifold gives you one unbroken pipe per fixture.
- Three or four fixtures and open pipework — tees will do.
- Buried in screed or plaster — manifold, and every branch a single length of pipe.
- Either way: a valve on each branch, and demountable joints only where you can reach them.
Common questions
What is in a flat's water inlet node?
In order: a ball valve on the riser, a strainer, the meter, a check valve, and — only if the pressure calls for it — a reducer with a gauge after it. Then the branching, with a valve on each branch. Cold and hot each get their own chain.
In what order do the strainer, the meter and the reducer go?
Strainer first, then the meter, then the check valve, then the reducer. Everything protects what comes after it: grit kills the meter impeller, and grit on the reducer seat means it stops holding the pressure it is set to.
Do I need a pressure reducer in a flat?
Only if the measured static pressure is above about 5 bar, or if it swings through the day. On a steady 3 bar a reducer improves nothing and adds a part to maintain. Lower floors of a tall building usually need one; upper floors usually do not.
Can I fit the meter myself?
You can do the pipework, but the meter is sealed and registered by the supplier, and nothing may be connected upstream of the seal. Build the node, then have it sealed — that order saves redoing it.
Should I leave the joints demountable?
Where you can reach them, yes. The meter comes out every four to six years for verification (the interval is set by the meter's data sheet and local rules), so it wants unions and a valve on each side. In a screed the opposite rule applies: no demountable joint gets buried, ever.