When getting quotes for a boiler replacement, we've been recommended to install a mains booster pump (e.g., Salamander HomeBoost). We live in a 3rd story UK flat and currently get a dismal 5 l/min flow rate, so the prospect of improving our flow rate/pressure is an appealing one, but I'm struggling to understand how a pump can increase the flow of water arriving to our flat in the first place. Is anyone able to explain the mechanism by which these systems work to somehow draw more water from the incoming system?

Thanks very much for any help!

  • My limited understanding of the typical UK water system is that simply being on the 3rd floor might tax the rather low pressure it's supplied at (which is not easily raised without consequences) - while many homes have been modernized, the plumbing in the street can't take much more pressure. If the politics of your building allow, placing the pump down where the water enters would be better than placing it in your 3rd floor flat. Pump suction has more limits than pressure does.
    – Ecnerwal
    Oct 28, 2020 at 12:56
  • What is the altitude of the water main inlet? What is the altitude of the faucet? Also, pressure and flow are not the same thing, in the same way that "how fast cars are going" vs "how many cars are on the road" are not the same thing. Oct 28, 2020 at 14:42

1 Answer 1


The assumption is that there is a restriction in the pipe and higher pressure differential across that restriction will lead to more flow.

If the restriction is downstream from the pump (a semi clogged valve for example) the operation is obvious.

If the restriction is upstream then the pump will draw a partial vacuum between it and the restriction which will increase pressure difference across the restriction up to some limit.

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