Changes to Chapter 109 – Safe Drinking Water Regulations

Posted by Natalie O'Connor on Wednesday, August 1, 2018

PADEP Chapter 109 DRR Rules

We’ve been hearing about the proposed changes to the Chapter 109 disinfection regulations for many years, but without concrete regulations, there was little anyone could do to prepare. So we were stuck, patiently waiting for policy makers to set the next obstacle course for us to navigate. Well the wait is over; we now know the challenges ahead, and it’s time to plan and take action, all in the name of better, safer drinking water!

On April 28, 2018, the Pennsylvania Department of Environmental Protection (PADEP) published [25 PA. Code Chapter 109] the Disinfection Requirements Rule (DRR), affecting ALL 2,695 Public Water Suppliers in Pennsylvania. While not all of the DRR requirements apply to every water supplier, it’s important to understand your new responsibilities. Some are immediate changes, while others require implementation over the upcoming year.

Here are some of changes that commonly affect water suppliers, and their compliance deadlines:

DRR compliance deadlines


Minimum entry point disinfectant residual:

  • Systems with surface water sources (SW) or groundwater under the direct influence of SW (GUDI) must maintain a minimum disinfectant residual at the entry point (EP) of at least 0.20 mg/L.
  • This increased from 0.2 mg/L to limit rounding of values. (Before 0.15 mg/L was compliant, since it rounded to 0.2 mg/L, this is no longer the case as 0.15 < 0.20)

Distribution system residual reporting

  • Begin reporting individual residual measurements instead of the number of measurements and the average result value.

Method 334.0 sampling methodology


Sample siting plan:


Distribution system minimum residual increase:

  • SW or GUDI systems must maintain a 0.2 mg/L residual Total Chlorine (TC) throughout the distribution system.
  • This increased from 0.02 mg/L.

what our clients are doing

New SDWA-1 Reporting:
One client is ready to comply with the new disinfection residual data submittal requirements, which went into effect in June 2018, but asked for our help developing spreadsheets personalized to their system in order to properly report Chlorine, Giardia and Virus Log Inactivation.

Understanding the Changes:
Another client asked, what’s this all mean? We went through, step-by-step with them, how the changes will affect monitoring, and reviewed potential operational changes and maintenance of the system that would improve water quality. We are considering:

  • Automatic flushing devices
  • Changing pipe routing to eliminate dead-ends
  • Booster chlorination station at a problem area in the system

Tank Mixing:
We are designing new tank mixing systems with chemical injection in several multi-million gallon storage tanks for a client who historically sees a significant drop in disinfectant residual readings during the warmer months. We are also evaluating ways to reduce their storage capacity, and operate the tanks in a different manner to decrease water age.

in the end

Maintaining good water quality in your distribution system has always been a monumental task, and now it just got a little harder. While there are dozens of solutions, you don’t want to spend a lot of time and money fixing the wrong problem. It’s critical to first understand what and where your problems are, which means collecting and analyzing lots of data. From there, a seasoned water engineer can take a holistic approach, and help you to make informed decisions to improve water quality and compliance. And as guardians of clean drinking water, this should be our goal every day.

If you’re wondering, Am I affected? or How am I affected? or What do I need to do and by when? We’d love to help!

additional resources

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Natalie O'Connor, EIT

environmental engineering designer

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Categories: Municipal Infrastructure

Tagged: Potable Water  |  Regulations

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