Pfizer produce pharmaceuticals at their site in Sandwich, Kent. This requires extremely pure water, called Low-Pyrogen Water (LPW), which is used to in the production process or to clean equipment.

Pyrogens are any impurities, such as fragments from bacteria, that could cause a fever or infection if they are taken into the body. Drugs must be free from pyrogens and so any water used in their production needs to be extremely pure. Low Pyrogen Water goes through stages of filtering, sterilisation with ultra-violet light and reverse osmosis. This ensures it reaches the levels of purity necessary for use in the production of medicines.

LPW was stored in vessels that periodically needed to be cleaned. The water was simply poured down the drain, but this wasted a huge amount of highly pure water. A system was installed that re-used this water for other uses around the site. This simple step saved over 3,500m³ of water per year. That is the equivalent of over 360,000 toilet flushes or approximately one and a half olympic-sized swimming pools.