# How does an inline water pressure booster pump increase outlet pressure without over-drawing the inlet flow?

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I am familiar with Bernoulli’s equation.

Given a main water inlet of a given diameter and in-house plumbing of a given diameter, how does a water pressure booster placed in-line after the main water inlet increase pressure through the rest of the house without drawing the inlet feed down to zero at some point (and effectively running dry or stuttering as the inlet struggles to feed the pump).

I figured for consistent pressure delivery that the pump would need to be paired with some sort of tank but many of the tutorials I’ve watched have simply placed the tank in-line and not used a tank.

EDIT: poor spelling 🙁

In: 1

Bernoulli’s equation doesn’t apply here. Bernoulli’s equation is derived from the principle of conservation of energy – that when the fluid speeds up, its pressure goes down or its potential energy goes down.

A pump is adding energy to the fluid, so Bernoulli doesn’t really apply. You’re adding external energy to the fluid and thus it doesn’t have to conserve its energy. You can get an increase in pressure without a loss of speed.

The reason you don’t have to worry about the inlet to your pump going dry is because your pump is hooked up to the city main – which is basically a limitless source of pressurized water. You’re never going to suck the water main dry. The fire department could *possibly* do it if they’re running several fire hydrants at the same time, but your residential booster pump never will.