EveryCalc

Finance category

Mortgage, loan, investing, tax, and money calculators.

Browse finance

Cooling Tower Water Treatment Cost Calculator

Cooling tower treatment is a recurring opex line that scales with tonnage and run hours.

$
$
$

Total annual cost

$73,000

Chemical cost

$7,000

Water + sewer cost

$66,000

How the math works

Ton-hours = tons × hours. Chemical = ton-hours × $/ton-hour. Blowdown = ton-hours × gal/ton-hour ÷ 1000 × (water + sewer).

500 × 4000 = 2M ton-hours × $0.0035 = $7,000 chemical + 6M gal/1000 × $11 = $66,000 water/sewer = $73,000.

How to Use

  1. Enter cooling tower tonnage.
  2. Enter annual run hours.
  3. Enter chemical $/ton-hour.
  4. Enter blowdown gallons/ton-hour.
  5. Enter water $/kgal.
  6. Enter sewer $/kgal.
  7. Read total annual treatment cost.

Frequently Asked Questions

Treatment cost drivers?

Chemicals (corrosion inhibitor, scale inhibitor, biocide): $0.0015-$0.005 per ton-hour. Blowdown water + sewer: 2-4 gal/ton-hour at $4-12/kgal combined. Energy for pumps + fans (separate): not in treatment but $0.04-0.10/ton-hour. Total treatment opex: $0.008-0.025/ton-hour. 500-ton tower at 4000 hours/yr × $0.015 = $30k/yr typical.

Cycles of concentration?

Ratio of solids in tower water to make-up water. Higher cycles = less blowdown but more scaling/corrosion risk. 3-5 cycles typical. 6-8 cycles aggressive (saves water but requires more chemical). Below 3: water waste. Above 8: scaling risk. Modern controls with conductivity meters automate cycles to optimum.

Legionella + biocide?

Legionnaires disease risk in poorly treated towers. Routine biocide dosing (oxidizing + non-oxidizing alternated): $0.001-0.003/ton-hour. ASHRAE 188 + state codes mandate management plans. Annual testing $1-3k. Outbreak liability: $5-50M+. Best practice: contracted treatment vendor with culture testing + risk assessment.

Water reuse opportunities?

Reclaim cooling tower blowdown for landscape irrigation: $5-25k retrofit. Captures 30-60% of blowdown water value. RO + UV reuse: $50-300k installs, 5-10 year payback in water-stressed markets. Condensate from AHUs returned to tower: free water recovery. ESG benefit beyond direct savings.

Related Calculators

More Finance Calculators

Browse all finance

Keep exploring

Next steps in Finance

View finance hub →