Yes it is. In high chloride water supply areas, the water can corrode some parts of the heat pump and tank, causing them to fail. Where the chloride level exceeds 200mg/litre, any warranty does not apply to the heat pump and tank units.
pH is a measure of whether water is alkaline or acid. In an acidic water supply, water can attack parts of the heat pump and tank, causing them to fail. No warranty applies to the heat pump and tank units where the pH is less than 6.5 or more than 8.5.
Water supplied from a rainwater tank in a metropolitan area is likely to be corrosive due to the presence of atmospheric contaminants in the water. Water with a pH of less than 6.5 can be treated to raise the pH. It is recommended that an analysis of water from a rainwater tank be conducted before connecting this type of water supply to a Reclaim Energy CO2 Heat Pump Hot Water System.