The Mesopotamians introduced the world to clay sewer pipes around 4000 BCE, with the earliest examples found in the Temple of Bel at Nippur and at Eshnunna, utilised to remove wastewater from sites, and capture rainwater, in wells.,
Ancient Greece: The ancient Greek civilisation of Crete, known as the Minoan civilisation, were the first to use underground clay pipes for sanitation purposes. They were also the first to utilise a flush toilet, in around the 18th century BCE, and used stone sewers that they regularly flushed out with clean water.
In 1676, Van Leeuwenhoek first observed water micro organisms. In the 1700s the first water filters for domestic application were applied. These were made of wool, sponge and charcoal. In 1804 the first actual municipal water treatment plant designed by Robert Thom, was built in Scotland.