October 2012
8-3
8.
Onsite Alternative Water Sources
Table 8-1. Water Quality Considerations for Onsite AlternativeWater Sources*
Possible Sources
Level of Water Quality Concern
Sediment
Total
Dissolved
Solids
(
TDS)
Hardness
Organic
Biological
Oxygen
Demand (BOD)
Pathogens
(
A)
Other
Considerations
Rainwater
Low/
Medium
Low Low
Low
Low None
Stormwater
High Depends
Low
Medium Medium
Pesticides and
fertilizers
Air Handling
Condensate
Low
Low Low
Low
Medium
May contain
copper when
coil cleaned
Cooling Tower
Blowdown
Medium High
High
Medium Medium
Cooling tower
treatment
chemicals
Reverse Osmosis
and Nanofiltration
Reject Water
Low High
High
Low
Low
High salt
content
Gray Water
High Medium Medium High
High
Detergents and
bleach
Foundation Drain
Water
Low Depends Depends
Medium Medium
Similar to
stormwater
Note: The use of single-pass cooling water is also a possible source of clean onsite water, but facility managers should first consider elimi-
nating single-pass cooling because of its major water-wasting potential. For that reason, it is not included in the list.
*
Key:
Low: Low level of concern
Medium: Medium level of concern; may need additional treatment depending on end use
High: High concentrations possible and additional treatment likely
Depends: Dependent upon local conditions
(
A): Disinfection for pathogens is recommended for all water used indoors for toilet flushing or other uses
