United States
Environmental Protection
Agency
RESEARCH PROJECT
National Risk Management Research Laborator
Water Supply and Water Resources Division
Treatment Technology Evaluation Branch
ASSESSMENT OF NITRIFICATION IN DISTRIBUTION SYSTEMS OF WATERS WITH
ELEVATED AMMONIA LEVELS
IMPACT STATEMENT
The drinking water industry has an interest in the fate of
ammonia (NH3) within the treatment and distribution of
drinking water. Research on the presence of ammonia in
drinking water distribution systems has suggested some
correlation between excess ammonia and increased
biological activity, corrosion, formation of nitrite and
nitrates and adverse effects on water's taste and odor.
Ammonia occurs naturally in some groundwater, or it is
added to water to form chloramines in drinking water
distribution systems. This study will provide the U.S.
Environmental Protection Agency (EPA) with, among other
things, better understanding of disinfectant loss from the
point of treatment across a distribution system, and the
effects of this loss on nitrification.
BACKGROUND:
Nitrification (microbiological oxidation of ammonia to nitrite and/or nitrate) in drinking water distribution systems is a
concern of many drinking water systems. Free ammonia enters a drinking water distribution system from naturally
occurring ammonia in the source water, adding excess ammonia during the process of chloramines formation for
microbial disinfection purposes, or breakdown of chloramines in the distribution system. Some types of bacteria can
growing in distribution systems can aerobically oxidize ammonia to nitrite and the nitrate when sufficient oxygen is
available. Aside from taste and odor complaints frequently accompanying nitrification, more potentially concerning
(from a human health respect) is the formation of nitrite and nitrate.
Four small drinking water systems in Illinois have reported excessive levels of free ammonia in their finished water
entering the distribution systems. The high ammonia levels are in the source waters and natural or associated with local
agricultural practices and natural reasons. The utilities report frequent odor and taste complaints, and preliminary
sampling of their distributed water suggests that nitrification is a problem (based on elevated nitrite levels). In some
instances, preliminary sampling at sites in the distribution system has in fact shown elevated levels of nitrite. The
utilities are aware of the potential related health concerns associated with excessive levels of nitrite and nitrate in their
distribution systems. They are also aware of the likelihood that nitrification can take place in their system which could
go undetected because regulatory monitoring takes place at the entry point into the distribution system. As a result the
utilities have looked to EPA for assistance in assessing the degree to which nitrification occurs in their respective
distribution systems.
National Risk Management Research Laboratory
Water Supply and Water Resources Division
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DESCRIPTION:
The objective of this work is to monitor ammonia, nitrite, and nitrate in drinking water from the distribution systems of
four drinking water utilities in Illinois. A monthly drinking water distribution system water quality monitoring protocol
for each water utility in Illinois has been established in most cases. Each water utility will provide six water samples per
sampling event: a plant effluent, and five sample locations along their distribution system. The samples will be measured
for pH, free and total chlorine, oxidation-reduction potential, and dissolved oxygen. The samples will then be submitted
into WSWRD's analysis system. Sample analysis will include ammonia, nitrite, nitrate and general ICP analysis.
EPA GOAL: Goal #2 - Clean & Safe Water; Objective 2.1.1- Water Safe to Drink
ORD MULTI YEAR PLAN: Drinking Water (DW), Long Term Goal - DW-2 Control, Manage, and Mitigate Health Risks
EXPECTED OUTCOMES AND IMPACTS:
Water utilities, states and engineers will better understand nitrification problems and approaches to reduce nitrification in
distribution systems.
OUTPUTS:
Current and future outputs of the project will consist of published papers, peer-reviewed journal articles.
RESOURCES:
NRMRL Corrosion Research: http://www.epa.gov/nrmrl/wswrd/cr/index.html
NRMRL Drinking Water Research: http://www.epa.gov/ORD/NRMRL/wswrd/dw/index.html
NRMRL Treatment Technology Evaluation Branch: http://www.epa.gov/ORD/NRMRL/wswrd/tteb.htm
CONTACTS:
Darren Lytle, Principal Investigator - (513) 569-7432 or lytle.darren@epa. gov
Steven Doub, Media Relations - (513) 569-7503 ordoub.steven@epa.gov
Michelle Latham, Communications - (513) 569-7601 orlatham.michelle@epa.gov
National Risk Management Research Laboratory
Water Supply and Water Resources Division
www.epa.gov/nrmrl
EPA/600/F-10/001
February 2010
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