This paper discusses how small systems can comply with the Safe Drinking Water Act regulations by forming cooperatives. The discussion is based on a project sponsored by the US Environmental Protection Agency involving mobile home parks in Pennsylvania. Mobile home parks comprise 32% of all small systems in the state. In the pilot project, owners of mobile home parks met once a month to discuss regulations and ways to comply with them. State regulators also attended the meetings. The author discusses lessons learned from the pilot project: 11 members is too small, each mobile park owner had important information to offer other owners and the regulators. Although this cooperative provided only a forum for discussion, other cooperatives with members that need financial help could organize joint laboratory contracts, shared operators, or collective purchases. In some cases, it may be necessary to have enforced cooperatives. Based on this pilot project, a guide to establishing cooperatives will be published by AWWA.