User Manual
45 
WATER SUPPLIES 
This  water  heater  must  be  installed  in  accordance  with  this  advice  to  be  covered  by  the  Rheem 
warranty. 
This  water  heater  is  manufactured  to  suit  the  water  conditions  of  most  public  reticulated  water  supplies. 
However, there are some known water chemistries which can have detrimental effects on the water heater 
and its operation and / or life expectancy. If you are unsure of your water chemistry, you may be able to obtain 
information from your local water supply authority. This water heater should only be connected to a water 
supply which complies with these guidelines for the Rheem warranty to apply. 
CHANGE OF WATER SUPPLY 
The changing or alternating from one water supply to another can have a detrimental effect on the operation 
and / or life expectation of a heat exchanger in a continuous flow water heater. 
Where there is a changeover from one water supply to another, e.g. a rainwater tank supply, bore water supply, 
desalinated water supply, public reticulated water supply or water brought in from another supply, then water 
chemistry information should be sought from the supplier or it should be tested to ensure the water supply 
meets the requirements given in these guidelines for the Rheem warranty to apply. 
SATURATION INDEX 
The saturation index (SI) is used as a measure of the water’s corrosive or scaling properties. The saturation 
index figures stated are calculated using a water temperature of 80°C. 
In a corrosive water supply, the water can attack copper parts and cause them to fail. Where the saturation 
index is less than –1.0, the water is very corrosive and the Rheem warranty does not apply to a copper heat 
exchanger in a continuous flow water heater. 
In a scaling water supply calcium carbonate is deposited out of the water onto any hot metallic surface. Where 
the saturation index exceeds +0.80, the Rheem warranty does not apply to a copper heat exchanger in a 
continuous flow water heater. 
Water which is scaling may be treated with a water softening device to reduce the saturation index of the water. 
Refer to the Saturation Index chart on page 45. 










