die Leistung – “performance, achievement, accomplishment”
die Leitung – “conduct, administration, line” (as in conduit or pipe) compare Leitung einer Firma, “direction of a company” and Leitung einer Flüssigkeit, “conduction of a liquid”
I’d used the second word to be very North American and order tap water in a restaurant – Leitungswasser – and upon learning its near sound alike, die Leistung, I immediately wondered what you would get if you ordered “performance water?”