Water pump voltage / pressure

Hi. I’m new to all this and will be starting up my own reach and wash business very soon. Just finding my feet at the moment. What do you all recommend with tank sizes. ( Small transit connect van ) hose length. Extending brush. Size of Water pump.  Nothing to expensive!!! Leaflet Advertising door to door ?  I’m thinking of using the pure water places local to me to start of with ? 
any advice is appreciated. 
thanks in advance 
 

As for tanks size you would need to check the van payload dependant on the model variant, typically the biggest tank you can realistically put in a small van is a 350ltr tank, I would also encourage you to scour the forum pages as this topic content has been covered multiple times previously