Since early July, neighbors in a Cedar Hills neighborhood were getting sick. In September, symptoms got worse. Several people have been diagnosed with giardia since then, but what was causing it and why was it was spreading was not clear. "We did find a cross-connect in (a) cluster of valves where there was a two inch lateral tied from the culinary irrigation to the pressurized irrigation," said City Manager David Bunker....The only common factor among the 13 affected houses was dirty yellow water. Simply put, a small, unknown pipe was allowing in secondary water. But the city didn't know about it. It was never identified on the construction plan. (Cedar Hills residents get giardia parasite from dirty water supply)