Chemical dosing at the water treatment plant is a critical, but often underrated step in producing safe drinking water. Historically, process control points have focused on the hazards present in incoming source water - with emphasis on the filtration and disinfection steps to minimize microbial risks. But while many hazards do indeed enter the plant with the raw water, it is just as important to identify the multiple risks associated with treating this raw water. One significant hazard in the treatment of water at the plant is overfeeding, resulting in discoloration, strong smells, or health hazards at the tap. Some of the most common root causes of overfeeding problems are pump or equipment failures, variations in water temperature, and source water characteristic fluctuations, to name just a few. In addition, bringing new technology online can sometimes trigger an event as well. This is why it is important to carefully document chemical handling and feeding information specific to your system on forms such as this one from the New Jersey Department of Environmental Protection. It is also essential to be on top of monitoring, chemical feed math skills and feed pump maintenance in order to correct situations as they arise (not to mention how to use activated carbon or sulfur dioxide to correct water quality issues). This resource from MASSDEP lists immediate action levels for water treatment plant chemicals. This tool from Missouri Rural Water can help you quickly size a chemical feed pump. This NCSE Tech Brief can help you calibrate a liquid feed pump. In addition, overfeed alarm systems are another solid choice for avoiding this problem. Finally, if and when an overfeed occurs in your system, prompt reporting can help speed up remediation. The Minnesota Department of Health provides this emergency response guide to its community PWSs in the case an event is affecting functionality or water quality. Learning who to call for help sometimes is the most difficult step in an emergency response situation, so preparing ahead can save you critical time and effort! *WaterOperator.org staff member Phil Vella contributed to this post.