World Water Day is marked each year on March 22 with 2015’s theme being water and sustainable development, an effort by the United Nations to bring attention to the need for new infrastructure to address water shortages resulting from such factors as pollution, decaying infrastructure, and shifting weather patterns.

The World Energy Council estimates that total power demand for water is expected to rise 100 billion cubic meters by 2050. There are several dedicated water exchange traded funds investors can use to tap the theme of surging water demand, including the group’s seasoned veteran, the Guggenheim S&P Global Water Fund (NYSEArca: CGW). [Evaluating Water ETFs]

CGW, the first dedicated water ETF to trade in the U.S., trackscompanies associated with the global demand for water, including water utilities, infrastructure, equipment, instruments and materials. While CGW, which turns eight in May, appears to be a niche play, investors have embraced the theme of investing in increasing water infrastructure needs and spending. CGW is home to almost $347 million in assets under management.

Home to 52 stocks, the ETF has a standard deviation of 11.66%, according to Guggenheim data. CGW’s holdings have an average market value of $10.4 billion, giving the ETF some exposure to the higher end of the mid-cap spectrum. That has been a benefit at a time when mid-caps are outperforming.

A lack of adequate public funding has been in focus as the demand for fresh drinking water rises, populations grow and water systems age and need repair. Industry is one of the largest users of water, followed by agriculture and residential. The cost of water is also rising alongside the costs of upgrades, while cities struggle to maintain budgets. [Best ETFs for Water]

Looking at water consumption , about 70% of demand goes into irrigation and farming while industrial demand takes up 22% and domestic use makes up 8%.