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Enhanced Water Main Flushing (Ice Pigging)

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1. What is ice pigging?

Ice pigging is a cleaning method for potable water distribution pipelines. The method involves pumping a slurry of ice into water pipes through a hydrant. Once in the pipes, system pressure is used to push the ice slurry downstream to exit through a different hydrant.

The ice slurry cleans material on the bottoms and sides of pipes using forces up to 1,000 times greater than flushing with water alone. Ice pigging results in more effective cleaning and uses significantly less water than traditional flushing methods. Like a glacier, the ice slurry incorporates the material and biofilm on the pipe into the ice mixture rather than bulldozing it.

2. What is in the ice pig slurry? Is it safe?

The ice pig slurry is very safe. It is made up of ice, water, and table salt (NaCl). For healthy individuals, the sodium intake from water is not significant, because a much greater intake of sodium takes place from salt in the diet. Individuals on sodium restricted diet, or those on dialysis should thoroughly flush their tap water prior to drinking.

3. Do other water authorities use ice pigging?

While ice pigging is a relatively new technology many other water authorities have successfully used this technique. The technique has been widely used across Europe (where the pipes are older) and has only been used in the United States for a couple of years.

4. Why is ACWWA ice pigging instead of flushing?

Over time, naturally occurring material can build up on the inside of a water main, impacting water flow and aesthetics (taste, color, odor, etc.). ACWWA traditionally uses a flushing method to remove this material. While the flushing method is adequate for short term fixes, ice pigging is an enhanced flushing method that is more effective at removing debris. This procedure should result in less maintenance on the distribution system and a higher quality water.

5. Does ACWWA need access to my service line?

No, ice pigging only requires access to the water main line.

6. Is ACWWA digging up any pipelines?

No. Ice pigging does not require excavation. The procedure puts the ice slurry into the water main through a hydrant and it is removed through a separate downstream hydrant.

7. How many feet of pipe is ACWWA ice pigging?

ACWWA will be ice pigging approximately 65,000 feet of water main lines. Even though this is less than 10% of ACWWA’s distribution system, it will address the areas of concern.

8. When is ACWWA performing the ice pigging?

Ice pigging will be performed on different sections of the distribution system at various times during the year. Please watch for postcard and door hanger notifications for dates/times that your area will be affected.

9. How will I be notified that the ice pigging is being done on my section of the water pipeline?

ACWWA will place door hangers on your front door the day before the ice pigging is performed on your section of the water main. Initial notification will be provided to the impacted customers by postcard mailers before the work is started.

10. Will the crews be working at night or on the weekends?

No, we are planning that all work will be done during the standard working hours during the week. If needed a weekend day may be required due to unusual circumstances and notifications will be given.

11. How noisy are the machines?

The ice pigging machines are quiet and will only be at a hydrant for approximately a half hour before they move to the next spot or are done for the day.

12. What should I do to prepare for my ice pigging day?

You should be prepared to not use any water from approximately 8 am to 3 pm. That means customers should have alternate sources of drinking water and be prepared to not do the following activities: irrigation, laundry, dishwashing, or other water uses such as showering or flushing your toilets.

13. Can I use my water during the ice pigging process?

No, while your water will still flow, it could contain sediment, salt, and ice from the ice pigging process and water use should be avoided during the above time frames during the days when ACWWA’s crews are working in your area.

14. How long will I be without water?

Each customer that has their water main cleaned, will be without water for approximately 2 to 4 hours during their scheduled working day.

15. Is the water from my tap safe to drink during the ice pigging procedure?

The water is safe to drink, but it will be aesthetically undesirable due to discoloration and potential elevated sodium levels.

16. What happens if I turn on my water while ACWWA is ice pigging?

The water coming out of your tap could be discolored, salty, and filled with sediment. It is recommended that you do not use tap water during this time.

17. Do I have to do anything special after the ice pigging procedure is complete?

Customers should run cold water through one tap (preferably the tap furthest away from the street) for 2 to 3 minutes after the completion of the procedure, prior to using the water for drinking or cooking. If a salty taste or discoloration is detected, run your tap for an additional 2 to 3 minutes.

18. Is my water safe to drink when the procedure is complete?

Yes, but before using your water, you should follow the procedure described in the previous question. After completing your in home flushing procedure, the water should be free of ice, salt, and sediment.

19. How often will ACWWA be using this technique?

ACWWA considers ice pigging a long-term maintenance technique that may be used every 10 to 15 years on an as needed basis.

20. What if my water is discolored after ice pigging?

After ice pigging activities, you may experience slightly colored or cloudy water coming from your tap. This is normal and does not pose a health hazard. You can reduce the cloudy effect by following the in home flushing procedure laid out in question 15.

21. What should I do if my water is discolored?

If discoloration occurs, try running only the cold water at one faucet for about 5 minutes and you should see that the water becomes clear. (Note that running the hot water, rather than cold water, pulls from the hot water heater and may delay or cause the water to not run clear.)

If the water doesn’t clear up after 5 minutes, wait for a few hours and try running the cold water only again. If the water is still discolored, please contact us so we can investigate why the water continues to have discoloration. Even if you are in an apartment or don’t pay your water bill direct, it’s important to let us know.

You may call ACWWA at 303-790-4830, or email us. email us.

22. Does this process have anything to do with changing my water supply like they did in Flint?

No, the ice pigging process is only being used to clean the water mains. The water supply will remain the same. While this process may result in some discolored water, the material causing the discoloration is not lead.

23. Why isn’t my area using ice pigging?

The ice pigging procedure is more costly than traditional flushing methods. ACWWA has limited funds and is prioritizing areas that need cleaning the most. Depending on the conditions of the water mains, ACWWA may use ice pigging on other sections of pipe in the future.

24. Will I get charged any more on my bill because you are doing this?

No, this expense is coming directly out of the operations budget and will not cost customers anything extra.

25. Will I need to change the water filter(s) on my ice maker, refrigerator, and tap?

No, customers should not need to change water filters. While indoor water filters and treatment devices as well as outdoor irrigation filters and sprinkler heads are susceptible to clogging during the cleaning process, additional flushing should fix any issues. Before using any filtration device, customers should follow the in-home flushing procedure described in question 15 to avoid filter clogging.

26. Who can I contact if I have additional questions?

ACWWA will update the website with information relevant to the areas that will be scheduled for cleaning as appropriate. Please contact ACWWA at 303-790-4830 or email us.