It is a normal occurrence after a major construction project to have debris/deposits in your interior plumbing flake off due to changes in water pressure or disturbance to the water main. The debris/deposits may contain lead. Flushing your water line, therefore, is important.
Lead can cause serious health problems if too much enters your body from drinking water or other sources. It can cause damage to the brain and kidneys and can interfere with the production of red blood cells that carry oxygen to all parts of your body. The greatest risk of lead exposure is to infants (particularly if they drink formula prepared with water containing elevated levels of lead), young children, and pregnant women.
For more information about reducing lead exposure around your home and the health effects of lead, visit USEPA's website at www.epa.gov/lead, the CDC website at www.cdc.gov/nceh/lead, call the National Lead Information Center at 800-424-LEAD, or contact your health care provider or local health department.