Find local pool plumbing service companies through Craigslist.org, Yelp.com and YellowPages.com. Yellow Pages and Yelp allow previous customers to leave reviews regarding their experiences with companies, which offers valuable information when deciding who to hire.
Before hiring a company for a pool plumbing job, contact multiple companies for quotes. Contact local businesses as well as national chains for a variety of quotes, and search for company reviews. Talk to friends, family members and co-workers who have hired a pool plumbing company in the past, and ask for recommendations.
When a company presents an estimate for the job, ask the company what it's charging for parts and materials. The companies' pricing for parts and materials include a mark-up, but prices can vary drastically from company to company. You can contact suppliers and request pricing for parts, then compare the prices to your quotes to estimate which companies are overcharging for materials.
Look for a company with years of experience and plenty of reviews from satisfied customers, but also research how the company deals with customers who have had negative experiences, as this information reveals a lot about the company. Be sure to get everything in writing before hiring a company, as written documentation can prove valuable if a conflict arises.