ALAMOSA, Colo. -- A Seattle law firm says it plans to sue this southern Colorado city over contamination of tap water that has sickened at least 276 people.

Marler Clark LLP said Wednesday it was mailing a notice of claim as a first step toward filing suit against the city of Alamosa. The case involves a child who was hospitalized for four days in the salmonella outbreak.

Lawyers say the boy, whose identity wasn't revealed, is recovering.

Alamosa City Clerk Judy Egbert said she had not seen the notice and could not comment.

The first salmonella victim began showing symptoms around March 8, and state health officials became aware of the outbreak a week later. At least 72 cases have been confirmed, state health officials said.

Chlorine Flushing Begins

Health officials started disinfecting the city water system with a high concentration of chlorine Tuesday morning after a salmonella outbreak traced to the town's tap water sickened more than 200 people.

Because of the heavy amount of chemicals that will be washing through 50 miles of water lines, officials told residents not to do anything but flush the toilets during the first stage of the cleansing process.

That means residents cannot shower, bathe, drink or even touch the tap water until officials give the all-clear signal. Touching the water could cause skin rashes, eye irritation or lung irritation.

Resident Laurie Duarte showed a crew from Good Morning America how she's forced to heat up bottled water on the stove to wash dishes. She also didn't know when she'd be able to shower again.

"So what I plan on doing is warming up water again, the gallon water warming it up and doing it that way," Duarte said.

The Alamosa School District has canceled school until Monday, March 31, because of the restrictions on water uses.

"The Alamosa School District is no longer able to implement universal precautions as the City of Alamosa will be limiting water usage to flushing toilets only. Therefore, our students would not have access to running water for hand washing," the school district said.

The flushing will occur neighborhood by neighborhood. Residents will know the water is unsafe by signs posted in their neighborhood.

A red sign alerts them to high levels of chlorine, approximately 25 parts per million (ppm).

As soon as yellow notices are posted in a neighborhood, it means the water is safe to use for bathing and swimming. Chlorine levels during the "yellow stage" will be approximately 10 ppm, or two to three times greater than the maximum level acceptable for drinking water, but slightly above the level found in a swimming pool. At this time, residents should run their bathtub faucet -- 5 minutes on hot, then 5 minutes on cold -- or until they smell chlorine. Some people may experience skin, eye or nose irritation from chlorine at this level, but may bathe with caution, authorities said. Tap water should not be consumed or used to brush teeth during the second stage. This stage is expected to last up to 10 days, but may last longer depending on results of the flush.

After that, neighborhoods will be given green safety notices that will mean the water is safe to drink. But those green notices are not expected to show up for another three weeks. It will take the city at least a week for tests to confirm the water is safe to drink.

Even then, residents are encouraged to run all taps in their homes for at least two minutes to charge their system with drinkable water.