Chemistries CLAROS                 800-227-4224

Distribution System Monitoring

Monitor water quality in the distribution system

Monitoring specific parameters at the Point of Entry (POE) is a Federal regulatory requirement to ensure the delivery of safe drinking water to the community. Monitoring water quality throughout the distribution system (beyond POE) is regulated by individual States and is accepted by municipalities as a good practice to maintain safety of the system and the product – tap water.

By monitoring treated water within the water distribution system, you can identify potential problems that pose risks to public health and threaten regulatory compliance.

Hach provides the solutions to monitor these parameters. With Hach, you can ensure that safe, quality drinking water is reaching your customers.

Explore What You Need
The SL1000 PPA performs multiple distribution tests faster.

Which Options are Right for You?

Your facility is required to monitor water in the distribution system to ensure safe drinking water for the community you serve. Thorough monitoring can also be an early indicator of serious issues, including nitrification, main breaks, excessive water age, or potential security violations. Whatever your needs, Hach is ready to help with information, technology, and support.

Explore parameters and methods for distribution monitoring below.

Distribution monitoring can provide early indicators of serious issues like nitrification, main breaks, excessive water age, or potential security violations.


Iron is tested for corrosion control and to assess if flushing procedures are sufficient in reducing the iron concentration to acceptable levels. Iron testing is also conducted at sites within the distribution system to investigate red water complaints from customers.

Find the right testing solution



Increased water turbidity levels within the distribution system can be an indicator of a water main break, nitrification or other deteriorating water quality conditions. Turbidity is also measured during flushing operations to ensure that it has decreased to acceptable levels before putting the line back into service. Check out Hach's turbidity monitoring solutions.

Find the right testing solution


Coliforms & Heterotrophic Plate Count (HPC)

Monitor pathogenic bacteria and HPCs to ensure that sufficient microbial protection has been achieved and crossconnection errors have not occurred after replacing distribution system mains and service lines.

Find the right testing solution



A decline in pH may be indicative of nitrification occurring in distribution systems using chloramination for disinfection. A sudden rise or drop in pH could also indicate a distribution system failure or security issue.

Find the right testing solution


Free Chlorine

Some utilities are required to maintain and report certain levels of free chlorine residual for systems using free chlorine for disinfection. Use the indophenol method 10241 for waters that have potential interference due to metals and/or chloramines. This method eliminates over-estimating free chlorine levels. The method also eliminates the use of arsenite for manganese interference compensation.

Find the right testing solution


Total Chlorine

Check for total chlorine residuals to meet compliance requirements. The maximum level allowed at POE is 4.0 mg/L. Many regulatory agencies require a minimum of 0.2 mg/L free chlorine or 0.5 mg/L total chlorine (monochloramine) throughout the distribution systems. Monitoring is also done at storage tanks and pump stations to study mixing efficiencies, water age, and temperature gradient issues. A sudden loss of disinfectant residual at any point within the distribution system can indicate nitrification issues, line breaks, excessive water age, or possible security violations.

Find the right testing solution



Compare the determined monochloramine value to the value at the POE. A drop in the monochloramine concentration indicates that there is a chlorine demand in the distribution system and the residual monochloramine has been used. A drop in monochloramine would be an indication that the free ammonia level has likely increased, which may indicate the onset of nitrification, and the situation may be out of compliance when only the total chlorine residual is measured by DPD method.

Find the right testing solution


Free Ammonia

Free ammonia levels will increase as monochloramine reacts with various organics and bacteria in the distribution system water satisfying the chlorine demand. Increased free ammonia levels indicate onset of nitrification. A sudden drop in free ammonia suggests that nitrification is in process and nitrite is being formed. The free ammonia value is useful in determining the amount of free chlorine needed to increase the monochloramine residual at a booster station. The free ammonia level can also be reduced by adding free chlorine in a ratio of 5:1 as Cl2: N to help reduce nitrification potential.

Find the right testing solution



Conduct nitrite monitoring as an early indication of nitrification. Keep concentrations at regulated levels to protect public health and avoid problems within the distribution system.

Find the right testing solution


Nitrite (NO 2)

Monitor your sources for nitrite as it may be present in the source and gets oxidized during treatment to produce nitrate.

Find the right testing solution



Mainly, groundwater facilities aim to remove dissolved metals and/or TOC with pre-oxidation, ion-exchange, or membrane treatment. However, some utilities may employ chemical treatment with coagulants. If your water source requires additional treatment with coagulants to remove colloidal particles, you can use advanced monitoring and optimization tools available from Hach.

Find the right testing solution




Explore additional parameters

For a full set of parameters to control water quality in the distribution system, review the information available with the Hach SL1000 Portable Parallel Analyzer Kit, designed to dramatically reduce potential errors in field analysis.




Additional Resources


A distribution system monitoring panel can help ensure integrity in your distribution system.

Ensure System Integrity with Distribution System Monitoring Panels

Learn how Pennsylvania's North Wales Water Authority used automated distribution system monitoring panels to monitor 50-square miles of service area.


Read the datasheet to learn more about the water distribution panel.

Download the Water Distribution Monitoring Panel Datasheet

The Water Distribution Monitoring Panel is the right tool to establish your distribution system's water quality baseline.


SL1000 PPA uses Chemkey reagents that execute tests without zeroing, mixing, shaking, chemicals, or vials.

Streamline the Distribution System Sampling Process

Learn how to streamline the sampling process. With the SL1000 Portable Parallel Analyzer, technicians can test multiple parameters with a single instrument. Complete more sets in less time and with less water.



SL1000 Portable Parallel Analyzer (PPA) Bundle Options

The full SL1000 PPA kit includes everything you need to get started with chloramination testing.

Full SL1000 Portable Parallel Analyzer™ (PPA) Kit

Everything you need to get started with chloramination testing.


Shop Now
The nitrification SL1000 PPA kit includes everything you need to get started with chloramination testing, including a nitrification probe.

Full SL1000 Portable Parallel Analyzer (PPA) Nitrification Kit

Everything for chloramination testing, plus a nitrate probe


Shop Now
The SL1000 PPA PhotonMaster kit includes everything you need to get started with chloramination testing, plus the LuminUltra microbial field testing kit.

SL1000 & PhotonMaster Kit

Everything from the Full SL1000 Portable Parallel Analyzer (PPA) bundle, plus LuminUltra’s microbial field testing solutions.

Shop Now

Select the attributes below to find the right distribution product for you.

Hach has a range of solutions designed for water quality experts! We help take the guesswork out of measurements with accurate results and simple operation so you can continuously monitor water in your distribution system before it goes to your community.


Compare our different products used for various applications by exploring the resources and options below.