Importance Of Maintaining Drain, Waste, And Vent Plumbing In Buildings

By Victor Hatcher and Brian Conner

In a building, the DWV (Drain, Waste and Vent) system is an often overlooked yet essential part of the sanitary infrastructure. Most DWV piping systems are hidden under floors, behind walls and in ceilings. Out of sight out of mind. Until your previously fully functional sanitary system has a problem.

The piping may not be visible, but like any other mechanical system, regardless of the material, your DWV piping should be properly and regularly maintained. You can keep an eye on your plumbing system by developing a DWV maintenance plan. This helps facility management effectively budget for your system maintenance and reduce the likelihood of plumbing emergencies that could upset your building residents.

Photo: Provided by the authors

DWV system assessment

There is no uniform maintenance program for DWV systems. The type and usage of building occupancy, piping material, and other special conditions unique to your building require evaluating your DWV systems as a first step.

Facility management can begin with a regularly scheduled visual inspection of the DWV system. Among other things, you are looking for a suitable slope, adequate support for the piping system and components, suitable ventilation and free ventilation openings and, of course, for visible leaks in the piping system. Regular visual inspections are just one step in a major effort to maintain your DWV system.

If your visual inspection shows no obvious signs of wear and tear, don’t assume you are clear. Many factors outside of the DWV system can adversely affect the DWV system and its long-term functionality. These factors form the core of the maintenance program. As conditions change, the frequency and manner in which you maintain your system should also change.

After completing your visual inspection, consider the risk factors that make your building unique. What are some of the considerations in determining the factors and frequency of your maintenance program?

• Cleaning chemicals. Strong cleaning chemicals with a pH range outside the normal range of expected sanitary effluents can damage the DWV system if not properly flushed.
• Grease the grease trap. These should be maintained according to the manufacturer’s recommendations so that the contents do not become septic. Proper disposal of food particles is key to an interceptor’s health.
• Gases from the municipal sewer. Some communities rely on the building’s ventilation system to vent gases from the sewer that can be harmful to the building’s ventilation lines as this is not the intended application. If these gases are in the system, regular purging should be performed to minimize the effects.
• Building use. Are the buildings occupied all year round or seasonally? If the usage is low, the DWV system may need to be serviced more frequently.
• Low flow or no flow fittings. The proliferation of low flow devices with no water for preservation has unintended consequences. Not enough water in the plumbing to clean or float the proverbial boat itself leaves microbes that can be harmful to your plumbing system.
• Soda fountains. Soda is typically a low pH liquid. In high concentrations, they can adversely affect pipes and fittings, especially if they are not properly flushed through the system.
• Commercial kitchens. High temperature liquids from pasta stations or commercial dishwashers can exceed the working temperatures of PVC DWV piping systems and lead to system failures.
• Hazardous waste. All wastes that are outside the range of normal sanitary sewage should be treated as such, with piping approved for the materials they are carrying. Special chemicals must be properly diluted before they enter the city sewer.

How to maintain your DWV system

There are tons of tools available that you can incorporate into a facility maintenance program. Here are just a few:

• Camera inspection allows you to look inside your piping system and identify problems that would otherwise remain hidden until it is too late.
• Nozzles, drain cleaning, cabling or rodding are also effective methods of cleaning, erasing, and maintaining your DWV system.
• magnet can be installed to introduce water to dilute, wash or clean the DWV system if necessary.
• Install ventilated barrel traps If you isolate the building’s DWV system from the city sewer, your community cannot rely on your building to vent gases into the city sewer system.
• Follow the manufacturer’s maintenance recommendations of dilution tanks that the building may have.
• Identify and replace aggressive detergents that the cleaning or maintenance personnel of the building may use a cleaning alternative with a neutral pH value.
• Consider installing upstream purge valves on soda fountains for proper dilution.

Many factors outside of the DWV system itself can have long-term effects on the performance and functionality of the system. Slope, system design, equipment, frequency of use, chemicals and cleaning agents, maintenance, materials, and water level and quality are just a few of the factors that can affect a DWV system. All of these influences and more must be investigated and properly assessed by facility management when creating an effective maintenance program for plastic or cast iron DWV systems.

The above information is not an exhaustive list of all factors to consider, but merely suggestions for formulating a maintenance program. It may be necessary to consult a plumbing professional when developing an effective DWV preventive maintenance program to keep your plumbing system from being up-to-date for the wrong reasons.

Hatcher has been in the plumbing industry for 19 years and has held several technical positions with plumbing companies and wholesalers. He is currently the codes and standards manager for Tyler Pipe and Coupling. Hatcher is a member of several standards committees, apprenticeship boards, and regularly participates in the plumbing and mechanical code development process.

Conner is Director, Codes & Standards and International Technical Support at Charlotte Pipe and Foundry Company. He has 15 years of experience in the sanitary industry as a producer, trainer and installer. Conner has extensive experience with national codes and product standards as well as specification work with the international engineering community.

To find out more about another aspect of plumbing in facilities, click here for “Tips for touchless plumbing retrofits” from the June 2020 issue of Facility Executive.