Low Water Pressure in a Sydenham Hill Top-Floor Flat

Weak water in a top-floor flat in Sydenham usually comes from three things working together: height, a shared supply and old, narrow pipework. Sydenham Hill is 112 metres up, near the top of the Norwood Ridge, so mains pressure is lower there to start with, and every floor you climb takes a little more off. In a converted Victorian house, one original supply often feeds every flat, so when the flats below run water, yours drops. Check your stopcock is fully open and your shower head is not scaled first; a lasting fix is usually a separate or larger supply, or an approved pump or accumulator agreed with the freeholder.

Why the top of the hill is different

Water pressure from the mains depends partly on how high you are compared with the reservoirs and pumping stations serving you. Sydenham Hill stands at about 112 metres on the Norwood Ridge, which peaks at about 116 metres near Crystal Palace. The streets at the bottom, towards Lower Sydenham and Bell Green, are a good deal lower.

So a ground-floor flat in Lower Sydenham and a top-floor flat in a tall villa near the summit are on very different footings. Inside the building, every metre the water climbs costs a little pressure, and a four-storey Victorian house is a long climb.

Why converted houses make it worse

Many of the big houses on Sydenham Hill and in Kirkdale were split into flats decades ago, without new supplies. Typically:

• one lead or iron pipe comes in from the street, sized for one household;
• it branches inside the building to each flat;
• the top flat is at the end of the longest, highest branch;
• old pipes have narrowed inside with scale and corrosion.

When the ground-floor flat runs a bath, the top flat’s shower can drop to a trickle. That is not a fault in your flat. It is the building’s supply being shared out.

What you can check yourself

1. Make sure your flat’s stopcock is fully open. Turn it anticlockwise as far as it goes, then back a quarter turn. People sometimes leave it half shut after a repair.
2. Check any isolation valves on your pipes are fully open: the slot should run along the pipe, not across it.
3. Unscrew the shower head and soak it in descaler or vinegar. Sydenham’s water is hard, about 255 to 263 mg/l depending on your part of SE26, and a scaled head can halve the flow.
4. Unscrew the aerators on the taps and clean them too.
5. Run the cold kitchen tap and note the flow. Then ask a neighbour downstairs to run theirs and see if yours drops.
6. Note whether the problem is on hot, cold or both. Hot only points to the cylinder, the boiler or a valve.
7. Check whether it is worse at certain times, such as weekday mornings, when everyone is using water.

Sudden drop, not a slow decline?

If the pressure was fine yesterday and is poor today, think differently.

• Check Thames Water first. Thames supplies this area. Look up your postcode on its website for planned work or incidents, and ask neighbours whether they are affected. Thames suggests trying the cold kitchen tap: if it runs but nothing else does, the problem is in your own plumbing.
• Think about a leak. A burst or leaking supply pipe somewhere in the building, or under the garden, can drop the pressure for everyone above it. Look for wet patches, a hissing sound or a water meter moving with taps off.

The fixes that actually work

A separate supply for your flat. The best answer, though the biggest job: a new pipe from the boundary to your flat, so you no longer share. It usually needs Thames Water’s involvement and the freeholder’s agreement.

A larger shared supply. Replacing the old narrow pipe from the street with a modern, larger one helps every flat. A good project for a building where all the leaseholders are frustrated.

Replacing old internal pipework. Narrowed iron or lead pipes inside the building can be replaced with properly sized copper or plastic.

An approved pump or accumulator. Pumps that draw straight from the mains are restricted under the water fittings regulations, so talk to us and Thames Water before buying one. An accumulator stores water under pressure for when you need it, which can help a top flat ride out the morning rush.

Because these change shared pipework, most need the freeholder’s or management company’s consent under the lease.

Is low pressure ever a leak?

Yes. A leak on the shared supply or under the front garden can be the reason pressure has been falling for months. If the meter moves with everything off in the whole building, there is a leak somewhere. We can trace it with acoustic and tracer gas equipment. Older Sydenham houses often still have lead supply pipes, which fail quietly.

Neighbouring guides

Joydens Wood in Bexley has the same high-ground problem in houses rather than flats. See our guide to low water pressure in Joydens Wood.

When to call

Call us if pressure has dropped suddenly and it is not a Thames Water incident, if you suspect a leak, or if you want a survey of the building’s supply. We cover water leaks in Sydenham and leak detection in Sydenham. More on the area is on our Sydenham area page.

Need a plumber now?

Call 07868 281022 and tell us your postcode, which floor you are on, whether the low pressure is hot, cold or both, and whether it came on suddenly. We agree the price with you before any work starts.