Controlling the Flow: Drip System O&M

Flow through a drip distribution system needs to be evaluated to make sure it matches design flow rate

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As I previously mentioned in the discussion of design considerations for drip distribution, loading and flow need to be controlled. This is done through use of flowmeters or a combination of cycle counters and elapsed time meters. Data about the total flow to the system and about flow to each individual zone within the field should be evaluated to see if the flow matches the design rate. This means the service provider needs access to the design values for comparison. Changes in flow rates can indicate whether emitters are plugging or if some zones are not receiving the proper amount of effluent. This may have already showed up in the visual evaluation of the field area. These numbers can confirm those observations and help determine what needs to be done to correct the system.

The hydraulic or electric switching valve should be checked to make sure it is switching between zones. In my part of the world we may only utilize a part of the system during the winter to minimize freezing potential, and it is important that they be switched back at the end of the season.

All drip distribution systems are set up so the lines can be flushed. These days, most of the flushing is accomplished automatically, but there were a lot of systems installed that need to be manually flushed. While at the site, the system should be manually flushed or run through an automatic flushing cycle. Operating pressures should be checked. Elevated pressures could indicate that emitters are plugging and additional flushing or cleaning may be necessary.

Air release or vacuum breaker valves should be checked. Make sure they do not leak when the system is pressurized. If they do they will need to be replaced. Check the field areas one last time for evidence of any leaks. Drip tubing is easily cut, which will allow the effluent to flow out in one spot. So as always, working with the homeowner so they know using probes or digging in the area can easily break a hole in the tubing is very important. Think kids poking objects into the soil for instance!

Finally, check to make sure all manufacturers' requirements have been met.

About the author 
Jim Anderson is connected with the University of Minnesota onsite wastewater treatment education program and is an emeritus professor in the university’s Department of Soil Water and Climate. Send him questions about septic system maintenance and operation by email to

This article is part of a series on drip distribution:


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