The reference guide lists Rainwater as a good non-potable water source for make-up water. The proposed cooling tower manufacturer raised the following concern for use of 100% rainwater and cooling tower condensate for make-up water: ‘Even though the towers are scheduled to be stainless steel, the corrosivity of the rainwater or condensate becomes a problem with the pH likely to be down around or below 6.0 (acid rain, corrosive) and containing very littles minerals. We don’t know the other materials of construction for the system, but assume mild steel and copper will be used. The rainwater will scrub the air as it falls and also pickup suspended solids as it is transported into the collection tanks. Biological growth in the tank is now a concern. The rainwater collection projects recently encountered have a blending system of the rainwater with the city water’. Based on this, the manufacturer is recommending 50% domestic water blended with 50% water from the tank. Is this acceptable? Thank you in advance for input.