Plant engineering calculator · Updated 17 September 2026
Cooling Tower Blowdown Savings Calculator — COC Water Savings
Compare cooling-tower blowdown at current and target cycles of concentration from evaporation and drift, then estimate annual water and cost savings.
Inputs
Live results
- Current blowdown 4.800 m³/h
- Target blowdown 1.800 m³/h
- Water saved 3.000 m³/h
- Annual water saved 15000 m³
- Annual cost saved 22500
Formula and method
For a simplified steady tower balance, blowdown B = E/(COC − 1) − D, where E is evaporation and D is drift. Savings are the positive difference between current and target blowdown.
Worked example
At 10 m³/h evaporation and 0.2 m³/h drift, increasing cycles from 3 to 6 cuts calculated blowdown from 4.8 to 1.8 m³/h, saving about 3 m³/h before site constraints.
Assumptions and limits
- Steady dissolved-solids balance with makeup concentration unchanged.
- Confirm target COC against water chemistry, scaling, corrosion, treatment and equipment limits.
Frequently asked questions
Does higher COC always save water?
It normally reduces blowdown, but chemistry and materials set practical limits.
Is drift included?
Yes. Enter measured or vendor drift loss separately so it is not hidden inside blowdown.