ARGHH!! HELP desperately needed!!?

Ok this is what we have to do for our chem ignment: write up a report on water quality we've already done tests and things and I know how I'm supposd to write up most of the information, but I can't exactly find the safe levels of phosphate in drinking water and water for recreational use!! if anyone can find it I would INCREDIBLY appreciate it!! i also need the recommended B.O.D. and conductivity. garrr! I woudn't usually bother asking I'd do it myself, but this ignment is HUGE and I'm running out of time! Oh and what do u usually do in an Experimental Plan?