On the mutual fund side, the biggest water fund is the Calvert Global Water Fund (CFWAX), which has $633 million in assets. Its portfolio allocations are similar to the water ETFs', but it has much higher fees. CFWAX has an expense ratio of 1.85 percent, plus a 4.75 percent front-end load.
When considering thematic or sub-sector ETFs, check for overlap with existing popular ETFs. You don’t want to buy into something you already own. Water ETFs pass that test ––their holdings have little representation in major broad market and sector indices. The most overlap is with industrial-sector ETFs, which hold a handful of these stocks.
-- FA Staff contributed to this story