Relative purity of water is discussed, based on its ability to resist electrical conductivity. Cited are differences in a typical municipal water supply with a resistance of 150,000 ohms; such water filtered with an in-line cartridge filter (250,000 ohms resistance); water processed in a stainless steel still (1 megohm); water triple distilled in quartz (2 megohms); triple distilled in quartz plus triple resin filters (13 megohms resistance), deionized water (18 megohms resistance). The purest possible water is recommended for quality photo processing. Also discussed are techniques for archival photographic processing. -- AATA