Using rainwater with and without a pump

Filling a watering can often works straight from a tap at the bottom. For a hose, sprinkler or several outlets, a suitable pump adds comfort. Choose the route that suits each garden.

Example layout

  1. Roof and downpipe
  2. Pre-filter
  3. HARVES Rainwall
  4. Tap or external pump
  5. Watering can, hose or sprinkler

Without a pump: gravity

Water flows from a suitable tap at the bottom as long as the water level is higher than the outlet. No electricity is needed. As a rule of thumb, one metre of water height gives about 0.1 bar of static pressure. While drawing water and as the level drops, pressure falls, and hoses, fittings and height differences cost pressure too. Ideal for watering cans, buckets and simple uses close to the wall.

With a pump: pressure and flow

A pump carries water to a hose, sprinkler or more distant outlet. Do not look only at maximum bar or litres per hour: the required pressure and flow must both be available where you use the water. Pipe length, suction height, dry-run protection and switching shape the choice. The wall itself stays unpressurised; the pump only pressurises the supply line.

Choosing the right pump

Rainwater tank pumps, surface pumps and automatic pressure pumps all exist. Which suits best is decided with your dealer or installer based on the wall connections and your use. We deliberately do not name a fixed model: suitability depends on your setup.

Useful to prepare

  • Where and how often do you use water?
  • What pressure and flow does your hose or sprinkler need?
  • Is there power at the location, or would you rather not?
  • How far away is the furthest outlet?

Harves supplies the water wall. Choose a pump, irrigation, controls and installation separately with your dealer or installer. Check the product information or quote for the exact parts included.

Frequently asked questions

Do I always need a pump?
No. For a watering can or bucket a tap at the bottom is often enough. For a hose, sprinkler or distant outlet a suitable pump helps.
Does Harves supply the pump?
No, Harves supplies the water wall. You choose the pump with your dealer or installer.
How much pressure does gravity provide?
As a rule of thumb, one metre of water height gives about 0.1 bar static pressure. Pressure available during use and as the level falls is lower; tap, hoses and height difference also matter.
Will every garden sprinkler work without a pump?
No. Many sprinklers require more pressure and flow than gravity supplies. Ask your dealer to match the sprinkler to an optional external pump; the water wall itself is not a pressure vessel.