Durham Region's Backflow Program by the Numbers (2026)
Records released by the Region put real numbers on the Durham backflow program: about 4,800 devices on an annual schedule, 1 in 4 past due in August 2026, roughly 125 past-due letters a month.
Most of what owners hear about the Durham backflow program arrives one letter at a time: a notice, a due date, a device serial number. What the program looks like as a whole has never been public. This year we asked, and the Region answered: records released under access-to-information request 2026-200 (September 2026), read alongside the staff report that set the program up (2018-COW-145, June 2018), put real numbers on it for the first time.
Here is what the Region’s own records show, and what it means if one of those letters has your address on it.
| Fact | Figure |
|---|---|
| Devices on an annual test schedule (August 2026) | 4,799 |
| Devices past their test due date (August 13, 2026) | 1,153, about 1 in 4 |
| Past-due letters sent since letters began in October 2019 | 8,824 |
| Past-due letters in recent years (2022 to 2025) | roughly 1,400 to 1,650 a year, around 125 a month |
| When a device is flagged past due | roughly 30 to 45 days after the due date |
| Heaviest stretch for due dates | March through June |
| Water connections the Region planned for in 2018 | 7,725 |
| Connections not yet on the annual schedule | roughly 2,900 |
| Program start | letters began October 2019; by-law effective January 1, 2019 |
| Notice types the program issues (Region’s written answer, September 10, 2026) | four: cross-connection survey due, notice to install after a survey, backflow due notice ahead of the annual date, past due after it; the Region describes all four as reminders |
| If no passing test is filed (Region’s written answer, September 10, 2026) | the device stays past due for about ten months, then its due date rolls forward to the following year so a new due notice can go out; it stays on file as untested |
| 2026 amendment (By-law 2026-023, passed May 27, 2026) | assigns each duty to a named party so violations can be ticketed with set fines under the Provincial Offences Act |
How big is the Durham backflow program?
About 4,800 backflow preventers were scheduled for annual testing as of August 2026, spread across all eight municipalities, from Pickering plazas to Brock farm-supply yards. Every one of those devices has its own anniversary, its own notice, and its own test report to file.
The program itself is the Region’s, run under By-law 24-2018 and administered day to day by BSI Online, which sends the notices and receives the reports. Our owner’s guide to BSI Online covers that side.
One device in four is past due
On August 13, 2026, 1,153 of those devices were past their test due date. That is about 1 in 4, or 24 per cent of the schedule.
Two things follow from that. First, if your building is past due, you are in large company, and panic is not the right response; a booked test and a filed report are. Second, past due does not expire on its own. A device is flagged past due roughly 30 to 45 days after the due date on the notice. It then stays past due for about ten months, after which the Region rolls the due date forward to the following year and a new due notice goes out. On the Region’s file the device is still untested; only a filed passing test resets it.
How the four notice types work
The program issues four kinds of notice, the Region confirmed in a written answer of September 10, 2026: a cross-connection survey due notice, a notice to install a device after a survey finds one is needed, a backflow due notice ahead of the annual test date, and a past-due letter after it. The due notice is the Region’s everyday tool. One goes out ahead of every annual date, and an owner who acts on it never sees the past-due letter at all. Our notice page reads each one line by line.
The past-due letter follows when nothing gets filed, and there are a lot of them: 8,824 since letters began in October 2019, roughly 1,400 to 1,650 a year from 2022 to 2025, around 125 a month, every month of the year. There is no quiet season.
The Region describes all four notice types as reminders. The by-law separately provides for orders, further notice, shut-off of the water service, and fines on conviction. In May 2026 the Region amended the by-law (By-law 2026-023) to spell out who is responsible for each requirement, so that violations can be ticketed with set fines under the Provincial Offences Act (Region of Durham, By-law 2026-023, passed May 27, 2026). The way to keep all of that theoretical is the same as the way to stop the letters. Test, file, done. Our step-by-step checklist walks through it.
The 2018 plan versus today
When the Region designed the program, staff report 2018-COW-145 planned for 7,725 water service connections at ICI and multi-residential properties. About 4,800 devices are on the annual schedule today, which leaves roughly 2,900 connections that have not yet been surveyed or scheduled.
The gap matters if your building is in it. Properties come onto the Durham backflow program through a cross-connection survey, and when the Region notifies you that one is required, the by-law gives you 90 days to have it done (section 5.2). A survey notice is not a test notice: surveys are done by licensed master plumbers, professional engineers or certified engineering technologists, not by testers. If you get one, act on it inside the window, and the annual test schedule follows from whatever the survey finds.
What this means for you
- Know your anniversary. Your device’s due date is the one date in the program that belongs to you. March through June is the heaviest stretch in the Region’s records, so if yours falls in spring, book ahead of the rush.
- If you are past due, only a filed passing test resets the device. Not the tag, not a phone call, not waiting. After about ten months the due date rolls forward to the following year, but that does not reset anything; the device stays on file as untested until the Region has a passing report.
- If you have never been surveyed, expect a survey notice eventually. Roughly 2,900 connections are still to come onto the schedule. When the notice arrives, the 90-day clock is real.
The numbers say the program is big, runs every month of the year, and never marks an untested device as anything else. The good news inside them: resetting a past-due device, or never becoming one, is one booked test and one filed report a year. If you have a notice in hand, our notice page explains it line by line, and the quote form takes about two minutes with a photo of the letter.
Questions this raises
How many backflow preventers are in Durham Region's program?
About 4,800 devices (4,799 in August 2026) were scheduled for annual testing across all eight municipalities. The Region planned for 7,725 ICI and multi-residential water connections when it set the program up in 2018, so roughly 2,900 connections have not yet been surveyed or put on a schedule. If your property has never been surveyed, the by-law requires a cross-connection survey within 90 days of the Region's notification (section 5.2). Figures from records released under access-to-information request 2026-200 (September 2026) and Region staff report 2018-COW-145 (June 2018).
What happens after the due date on my notice passes?
The device is flagged past due, usually 30 to 45 days after the date on the notice, and the Region sends a past-due letter. If no passing test report is filed, it stays past due for about ten months; the Region then rolls the due date forward to the following year and sends a new due notice, and the device remains on file as untested. Only a filed passing test resets it. The Region describes its notices as reminders; the by-law separately provides for orders, further notice, shut-off of the water service, and fines on conviction. Figures from records released under access-to-information request 2026-200 (September 2026) and the Region's written answer of September 10, 2026.
When are most Durham backflow tests due?
Due dates run all year, but March through June is the heaviest stretch. If your device's anniversary falls in spring, book ahead of the rush. Pattern from the August 2026 export released under access-to-information request 2026-200 (September 2026).