Substantial information now exists on the use of simplified drainage systems in low-rise and multi-storey domestic buildings, and much of this is summarised in Digest 80, Soil and waste pipe systems for housing. The present digest deals with the design of soil and waste pipe systems for office buildings. Ranges of appliances, each individually vented to a separate vent stack, are typical features in a traditional layout. BRS work has shown that much of this vent piping is unnecessary or can be reduced in diameter. For an eight-storey installation, using copper pipework, simplified design has been shown to effect a 40 per cent reduction in cost.