Cooling Tower Water & Operating Cost Calculator
Work out how much water your cooling tower evaporates, bleeds off and consumes, what that costs each year alongside fan energy and water treatment, and how much you would save by running more cycles of concentration.
Inputs
Defaults describe a mid-size industrial tower. Replace them with your own meter readings and utility rates. For the formulas and how to read the results, see the cooling tower makeup water and blowdown guide.
Tower and water balance
Costs
Cost Breakdown and Cycles Savings
Makeup water purchased per year.
Blowdown discharged to drain per year.
97,304 kWh per year.
As entered.
Saves about 408,000 gal of makeup water and the same volume of blowdown each year, worth roughly $4,488 in water and sewer charges. Higher cycles raise scaling risk, so confirm the limit with your water treatment supplier.
Formula Notes
Heat rejection (Btu/h) = 500 × gpm × range (°F). 500 comes from 8.33 lb per gallon × 60 minutes × 1 Btu per lb·°F.
Evaporation (gpm) ≈ 0.00085 × gpm × range × load. A rule of thumb: roughly 1% of flow evaporates per 10°F of range. Real towers vary with weather because some heat leaves as sensible heat rather than evaporation.
Blowdown = evaporation ÷ (cycles − 1) − drift, and makeup = evaporation + blowdown + drift.
Fan power = hp × 0.746 ÷ motor efficiency × average power fraction. Fan power falls with roughly the cube of speed, so a fan on a VFD at 80% speed draws about half its full-speed power.
Use This Output in Context
This is a screening estimate. Metered makeup and blowdown flows always beat the evaporation rule of thumb, and many utilities give sewer credits for evaporated water only when both are metered.
If the tower serves a chiller, run the industrial chiller operating cost calculator as well, and compare with the air-cooled vs water-cooled chiller comparison if you are still choosing a system.