A clever and perhaps misleading Pur water filters TV campaign puts a fine point on the importance of being informed about your tap water quality.

The video shows unwary patrons walking into a swanky, faux Manhattan “water bar,” where a bartender offers them tap water “varieties” from throughout the United States. He then wryly assures them that the contaminants in the water are well within acceptable legal limits.

The punch line is this: “Water that meets safe drinking standards may not meet yours.”

It’s true that “safe” can mean different things to different people. When it comes to water, some people believe that every contaminant detected at any level is hazardous, eschewing the toxicological principle that “the dose makes the poison.” And so, they reason, why not purchase a home treatment device for a little added protection? For others, water that meets all of the standards under the Safe Drinking Water Act is perfectly acceptable, and they’d prefer to spend their money on something with more proven benefit.

We all get to make that decision for ourselves. But here’s some nuggets to help you make an informed choice when it comes to home treatment devices.

• First, get to know your water. Your water provider can explain the results of your community’s annual consumer confidence report and let you know if there were any violations of the Safe Drinking Water Act. You don’t want to buy a home filter to remove something that’s not in your water in the first place, or not at a level that is concerning to you.

• If you do choose to purchase a home filter, make sure it is independently certified for the intended purpose. NSF International has an excellent guide to help. Remember: Every filter will not remove every contaminant at every level.

• Some old homes have lead in their pipes or plumbing, and in some instances, that lead can dissolve or break off into the water and end up at the tap. Even low levels of lead are harmful, and a filter certified to remove lead can be effective at reducing exposure. You may want to have a certified laboratory test your water or hire a certified plumber to look for lead materials before making a purchase. In the long-term, the best choice is to remove the sources of lead.

• Home filters must be properly maintained to remain effective. Make sure you pay attention to the manufacturer’s instructions.

Finally, beware of door-to-door pitchmen or telemarketers who offer to test your water and install their own treatment devices. Like that very clever water bartender, they have something to sell.