Some noncommunity public water supplies are required to add treatment to protect public health or choose to add treatment for other reasons.  A construction permit is required before installation of water treatment equipment that injects chemicals or is required to meet a health based standard such as arsenic or nitrate. Water supply owners should consult with regulatory staff when deciding whether to install treatment equipment to ensure they understand all the legal requirements. Water treatment systems that require a construction permit to install must also meet legal requirements after the treatment is installed such as having a certified operator, sampling, and submitting monthly operation reports.