There are 2 answers :
1 BOOSTER PUMP :
A booster pump goes before the RO and increases the pressure in the RO, thereby giving more pressure on the other side of the RO (pure water.
An RO works as a result of a pressure differential across the membrane - so the more the ‘difference’ the greater the production.
The only problem is that this formula is seriously interfered with by the temperature of the IN WATER - in our case, the temperature of the ground water from the spigot.
The production of an RO in Laboratory Conditions is designed at 77ºF (lets say it is rated for 2500gpd) but at 39ºF, the very same RO will only produce 50% (1250gpd) due to the increased viscosity of the water.
So … a booster pump will increase the pressure before the RO, with consideration to the temperature, and the ‘head’ of pressure pushing back from gravity on the pure water line (this is back pressure that reduces the pressure differential ) .
2 DELIVERY PUMP
A Delivery Pump cannot have any pressure behind it … it is a ‘push’ pump only.
So … to use a Delivery Pump, you need a TANK - just a small buffer tank 35 gallons to 50 gallons is fine …
Now the RO is filling the BUFFER tank, not pushing water up a tube - so there is no 'back pressure from the head of gravity. As a result, the RO can perform better (but still affected by water temperature) .
NOTE TO SELF : You do not need an RO system to use a buffer tank … you can also feed DI WATER into the buffer tank.
The delivery pump is now dedicated 100PSI to your delivery of purified water to the pole and brush jets.
Now the going gets better … if you have the Delivery pump - you can add a Pump Controller - if you use the right type, the greater the resistance (eg Head of Gravity), the more amps the controller delivers to the pump so the pressure, flow, and velocity of water from the jets is CONSTANT - regardless of your working conditions …
One Delivery Pump per operator , and you can have 2 operators working at different heights … remembering water finds the path of least resistance, so it will always flow more out of the lower brush if all other conditions are equal …
I hope this helps …