Editor's note: The following are questions received from viewers of "Mad Money," seen every day at 6 p.m. EST on CNBC.

What do you think about the Powershares Global Water Portfolio (PHO) - Get Report exchange-traded fund?-- Mary from Louisiana

James J. Cramer:

I believe this new exchange-traded fund is an attractive way to invest in a basket of water stocks. We're currently in a market where resource-based companies are king, and clean water is a scarce asset that will always be in demand.

It's worth noting, that I own

Aqua America

(WTR) - Get Report

, the largest publicly-traded water utility and also a large holding of PHO, in my

Action Alerts PLUS charitable trust.

What is the impact on a stock when it is mostly held by large institutions? For example, 91% of Oregon Steel (OS) is controlled by fund managers.-- Andy from British Columbia, Canada

James J. Cramer:

One result of this could be increased volatility around the end of reporting periods. Most institutions close their books for any given month, quarter or year around the same time. Some firms also try to juggle their holdings, so they show they own well-performing stocks and close out of losers right around the reporting deadline.

Want more Cramer? Check out Jim's rules and commandments for investing from his latest book by

clicking here

.