[marc al]

  I have a 60psi pump with an integrated pressure switch but cannot adjust the flow rate, I have found that I am using more water than I really require, what is the best way of slowing down the flow?

[Roy Harding]

You can fit a flow control valve or this company does a unit

http://www.williamsonpumps.co.uk/WATERFEDPOLE.html

[Ian_Giles]

I've just done a reply to a similar question with another possible solution.

Roy has just given you one, but there is another way too,.....er....When I say that Roy has just given you one, I of course mean a different solution to the one I am mooting, and not something entirely different

I'll post it in more detail on the other thread, need to take some photo's first though

Ian

[Jeff Brimble]

See other topic answer for pump, Make yourself a by pass(or 2 depending on output of pump).
Also put a small valve/tep at the brush head so you have control/on/off  at a distance.
You can do this with hozelock micro irrigation parts from B&Q or good garden centre.