Recent investigations have found that organic chemicals may contaminate drinking water by permeating buried plastic pipes and gasket materials. Pipe--bottle direct-exposure experiments and microbalance experiments were conducted in order to determine the susceptibility of polybutylene (PB) piping material and gasket materials to permeation by a wide range of organic chemicals. Many lipophilic compounds tested were found to permeate to a detectable level in consumers' tap water within a month at one third of their aqueous solubilities. It was also found that PB was more permeable than low-density polyethylene to toluene and that chlorinated hydrocarbons permeated PB faster than unchlorinated hydrocarbons. Gasoline compositions such as benzene, toluene, ethyl benzene, and xylenes appeared to be highly permeable to PB and gasket material. The organic chemicals were approximately 5 to 100 times more permeable in gasket materials than in PB. Includes 19 references, tables, figures.