We have a house up on Branch Lake in Maine and it is lake water supplied. We have a filter to take out debris and an UV sanitizer. Lake fed houses are very popular up there. I mean really how'd the old settlers do it? But as mentioned the water quality is certainly not as good as it was a hundred years ago. Acid rain, polution, heavy metals etc. Just make sure your system is a good one and drink bottled water or boil it. I found these....
http://www.equinox-products.com/LakeWaterSystem.htm
http://doultonusa.com/HTML%20pages/C...%20filters.htm
I wonder if a filter system from a pool would work as well. Can't see why not. At least for debris. Just requires cleaning every once in a while.