Clean and consistent water supply is an essential service of modern living, so the industry remains untouched by economic fluctuations.

According to IBISWorld, the industry should see steady 3.5 percent revenue growth per year until 2015. Although traditionally the industry has been dominated by municipally owned operations, there may be increasing opportunities for independent companies to enter the market as it trends toward privatization.

Why? Challenges in adhering to stricter water-quality standards could drive cities to look elsewhere for solutions. They will also probably face hardships in keeping up with technological developments. Tech and consulting are two hot areas for breaking in.

By the numbers:

Percentage of industry revenue accounted for by top five industry players, according to IBISWorld: 6

Average profit margin for "water supply and irrigation systems," according to IBISWorld: 11.5 percent

Percentage of U.S. water use accounted for by household sector: 60

Expected annual industry revenue growth to 2014, according to IBISWorld: 3.4 percent