Interactive Calculator · 2026
STP Lifecycle Cost Calculator
The price on the quotation is only the beginning. This calculator adds the years of operating cost an STP racks up over its life to the upfront capex — and subtracts what you save by reusing treated water — to show the real lifecycle cost.
Your plant's costs
Supply, install and commission the STP.
Power, chemicals, manpower, sludge disposal, spares.
Design service life before major replacement — typically 15–20 years for a well-run STP.
Freshwater and tanker purchases avoided by reusing treated water for flushing, landscape and cooling.
Where the lifecycle cost goes
Capex is only 19% of the Rs 1,30,00,000 whole-life cost — the rest is 15 years of running the plant.
A cheaper plant that costs more to run every year can easily end up the more expensive choice once you count the full 15-year lifecycle — which is why opex, not just the sticker price, decides the real cost.
Reusing treated water claws back Rs 1,35,00,000 over the life, bringing the net cost down to Rs -5,00,000.
How this is calculated
- Total opex over life = annual opex × years = Rs 7,00,000 × 15 = Rs 1,05,00,000.
- Gross lifecycle cost = capex + total opex = Rs 25,00,000 + Rs 1,05,00,000 = Rs 1,30,00,000.
- Total reuse savings = annual saving × years = Rs 9,00,000 × 15 = Rs 1,35,00,000.
- Net lifecycle cost = gross LCC − reuse savings = Rs 1,30,00,000 − Rs 1,35,00,000 = Rs -5,00,000.
Simple (undiscounted) lifecycle cost for concept comparison. A full appraisal would also apply a discount rate, inflation on energy and chemicals, and mid-life replacement of major equipment — confirm with a qualified consultant before procurement.
Related Guides — Deep-dive reading
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