The state wants to know how many people in New Hampshire test and treat their wells and see if there are obstacles to testing that can be overcome.

The departments of Environmental Services and Health and Human Services, using part of a $200,000 grant from the Centers for Disease Control and Prevention, hired a team from Dartmouth to survey well owners. The contract with Dartmouth is worth $93,000.

More than 40 percent of the state's 1.3 million people use private wells and about 20 percent of those contain unsafe levels of arsenic, according to the state. That naturally-occurring element has been linked to skin, bladder and lung cancers.

Well water can also contain high levels of radon, which is blamed for about 100 deaths every year in the state.

The aim of the survey is to help design cost-effective, targeted ways to help well-users monitor and protect their drinking water.

"We want to learn how to empower well-water users with the tools and information they need to keep their drinking water safe for themselves and their families," says project leader and Dartmouth engineering professor Mark Borsuk.

Borsuk said researchers are hoping to get responses from three groups: All well users, people who've had a well dug within roughly the past decade and those who have gotten or are getting wells tested this summer.

"We're trying to understand what we could do to motivate them to get the tests," he said.

Borsuk said wells should be tested every three to five years. If unsafe levels of arsenic or radon are detected, there are several treatment options including filters and other ways to absorb the elements.

The online survey is open to all New Hampshire well-water users, although several thousand residents have already received postcards specifically inviting them to participate.

"Arsenic in private wells is a significant public health issue in New Hampshire," said DES Commissioner Thomas Burack.

New Hampshire residents can take the survey at: www.surveymonkey.com/s/nhwellsurvey.

The survey will close on June 30. Preliminary results are expected in mid-July with a final report due at the end of August.

Dartmouth's Superfund Research Program has been examining the health effects of arsenic for the past 17 years.