The first water ETF celebrates its five-year anniversary this month.

Invesco PowerShares Capital Management says its PowerShares Water Resources Portfolio (PHO), listed on December 6, 2005, is the largest and most actively traded ETF providing investors with access to a portfolio of U.S.-listed companies in the water industry.

The ETF, with about $1.2 billion in assets, is based on the Palisades Water Index and will normally invest at least 90% of its total assets in ADRs and common stocks in the index, which seeks to identify a group of companies that focus on the provision of potable water, the treatment of water, and the technology and services that are directly related to water consumption.

According to Morningstar, PHO returned 4.92% annualized for the five years ended December 8, compared with 1.69% for the S&P 500.

"The world's supply of clean water is increasingly in demand for consumption, irrigation and industrial production, and we believe the PowerShares Water Resources Portfolio is a compelling way for investors to capitalize on this investment theme," says Ben Fulton, Invesco PowerShares managing director of ETFs.