The climate crisis is fueling extreme weather events including record droughts, and with stress growing on global water systems HSBC said investors should own stocks with exposure to water infrastructure. In a recent note to clients, the firm said water systems are a "huge investment" theme over the coming years, identifying key players in various sub-sectors of the over-arching theme. The firm noted that revenue across its water-focused basket of stocks has risen more than 30% since 2014 - 2015 as spending rises for antiquated systems that are unable to withstand extreme weather events and rising global temperatures. "Climate change is associated with widespread changes in worldwide weather patterns, leading to water scarcity, droughts and floods, as well as contamination of water supplies," the firm said in a note to clients. "We think companies that offer water management solutions across various industries could gain from rising awareness about addressing the global water scarcity issues," HSBC added. Water systems are complex, and investing around the theme can mean picking companies in different industries. HSBC defines the broader theme as investing in companies that "provide products and services for drainage, storm water, flood protection, desalination and dredging." It also includes water infrastructure companies that provide pipes, pumps and meters, as well as those that deal with water purification, wastewater treatment and reducing leaks. American Water Works is one of the companies that HSBC pointed to. The Camden, New Jersey-based company is the largest publicly-traded water and wastewater company in the U.S., providing water and wastewater services to 14 million people across 24 states. Investors typically flee to defensive areas of the market during times of uncertainty, but American Water Works has not escaped the recent selling. The stock is down about 8% over the last month, and more than 25% for the year. HSBC also pointed to water treatment company Ecolab and water solutions company Xylem as beneficiaries of increasing investments in water infrastructure. Smart solutions, like those that Xylem provide, are a growing area of focus as municipalities look to upgrade their water systems. The U.S. drinking water system loses 2.1 trillion gallons of water per year thanks to leaks and faulty pipes, according to the American Society of Civil Engineers. Shares of Xylem are down 25% this year, while Ecolab has shed 37%. For investors looking for more general exposure, there are several ETFs that track the space, including the First Trust Water ETF , the Invesco Water Resources ETF and the Global X Clean Water ETF . - CNBC's Michael Bloom contributed reporting.