Given that pure water is never a waste, when installing a water purifier for domestic use, a small tap is supplied and installed on the kitchen sink, allowing the purified water to be dispensed separately. More precisely, the existing tap continues to be used for all "non-food" uses of water from the aqueduct and the purifier tap only for water intended for human consumption (drinking and cooking). However, there are taps on the market that replace the existing tap and allow the supply of one or the other water (three-way taps, five-way taps, etc.).