Its called the Dirt Worker, got it for 50 quid from Halfords, its used for cleaning Bikes etc.
Normally it gets its voltage from the Car, I changed the Cabling and added a Gel Battery which I bought from a Retailer selling Disabled scooters; they have them on mass second hand for a 10er.
There is a 70psi pump inside, with an on and Off switch.
I use a Valve to reduce the water flow.
Can be adapted to any WFP Pole.
Holds 17 Liters of Pure Water.