How long does it take for the investment in a treatment plant to pay off?

If you are switching from a cesspool to a wastewater treatment plant, the annual savings are €500–1,080. The difference in the initial investment between a cesspool and a WWTP is approximately €2,000. The investment therefore pays for itself in 3 to 5 years. Once the investment is paid off, you save €500–1,000 per year over the entire lifespan of the treatment plant, which is 20–30 years. Total savings over its lifetime can reach €10,000–25,000.