A condensing appliance can produce up to one gallon of condensate for every 100,000 BTUs, or therm, of gas consumed. This condensate is acidic, generally in the range of 3.8 to 4.2 pH, although we have seen some as low as 1.8 pH. To prevent damage to piping, sewer, and septic systems, the condensate needs to be in the range of 5 to 7 pH.