Caesar - with a sheet of plastic - no holes in it thank you, you could have collected rain water. <img src="/forums/images/graemlins/shocked.gif" alt="" />

Or even dug a hole and poured in a bunch of icky <img src="/forums/images/graemlins/blush.gif" alt="" /> water and then covered with the plastic tarp so that its lowest point drips collected distilled water into your pan. <img src="/forums/images/graemlins/tongue.gif" alt="" />

Were you in a place where you had access to course sand? You could prefilter your water through sand. <img src="/forums/images/graemlins/grin.gif" alt="" />
Jim <img src="/forums/images/graemlins/cool.gif" alt="" />