Dividend investing is a tried-and-true strategy for generating strong, steady returns in economies both good and bad. But as corporate America's slew of dividend cuts and suspensions over the past few years has demonstrated, it's not enough simply to buy a high yield. You also need to make sure those payouts are sustainable.

Let's examine how Mueller Water (NYSE: MWA) stacks up. In this series, we consider four critical factors investors should examine in every dividend stock. We'll then tie it all together to look at whether Mueller Water is a dividend dynamo or a disaster in the making.

1. Yield
First and foremost, dividend investors like a large forward yield. But if a yield gets too high, it may reflect investors' doubts about the payout's sustainability. If investors had confidence in the stock, they'd be buying it, driving up the share price and shrinking the yield.

Mueller Water yields 2.6%, a bit higher than the S&P 500's 2.1%.

2. Payout ratio
The payout ratio might be the most important metric for judging dividend sustainability. It compares the amount of money a company paid out in dividends last year to the earnings it generated. A ratio that's too high -- say, greater than 80% of earnings -- indicates that the company may be stretching to make payouts it can't afford, even when its dividend yield doesn't seem particularly high.

Mueller Water doesn't have a payout ratio because it didn't generate earnings last year. On a free cash flow basis, however, the company paid out 127% of its free cash flow.

3. Balance sheet
The best dividend payers have the financial fortitude to fund growth and respond to whatever the economy and competitors throw at them. The interest coverage ratio indicates whether a company is having trouble meeting its interest payments -- any ratio less than 5 times is a warning sign. Meanwhile, the debt-to-equity ratio is a good measure of a company's total debt burden.

Mueller Water has a debt-to-equity ratio of 179% and an interest coverage rate of 0.2 times.

4. Growth
A large dividend is nice; a large, growing dividend is even better. To support a growing dividend, we also want to see earnings growth.

Over the past five years, Mueller Water's dividend has held constant at $0.18 per quarter, but the company has been generating losses since 2009.

The Foolish bottom line
Given the losses the company is taking, as well as the fact that operating income is dwarfed by its interest costs, Mueller Water certainly isn't a dividend dynamo. If possible, it should even consider halting its $10.9 million in annual dividend payouts to help shore up its business. However, if you're looking for great dividend stocks, check out "Secure Your Future With 11 Rock-Solid Dividend Stocks," a special report from the Motley Fool about some serious dividend dynamos. I invite you to grab a free copy to discover everything you need to know about the 11 generous dividend-payers -- simply click here.