Installing backflow valves

Recently we had two units flooded due to root penetration in one of our sewage lines on the property. The result was approximately 4 inches of sewage throughout the first floorof a resident's unit. The responding plumber recommended we have check valves or backflow valves installed in three lines to units. I am interested in hearing from anyone that may have done thisregarding who paid for the valves and their installation. We are located in North Carolina. Our units were constructed in 1984.

Robert,

The backflow valves for the common areas are installed by the developer and maintained by the HOA. In a community of single family homes, each homeowner would have a backflow valve for his property that he would be resp. for.

Being a condo community, I would say it would be the resp. of the HOA to install these backflow valves if the HOA is resp. for plumbing.

Thank you for the questions. While we have had some root "issues", they before now were restricted to the water lines between the units and the main line and not in a sewage line. I did speak with someone with the State today and was told that check valves should have been installed if the unit water outlets were "lower than the manholes". That certainly raises more questions as I go look for my tape measure ! Obviously, I will have to call a plumber back out to try and ascertain whether or not we have such a condition. It is not possible to tell by visual inspection as the lines are at various depths down inside the manholes.

Calling a plumber out and asking if we need check valves feels like driving into a car repair shop and asking a mechanic if he can find any problems with my car. I am betting I am told of course we need them.

I have heard of some associations paying for routine maintenance on the sewer lines in hopes of heading off something such as what we experienced. I will be looking into that as well.

Fortunately, the resident was well insured. Everything touching the floor on her first level ended up at the dump. I will be working on preventing this happenning again will try and post an update.

RobertS, As I understand your question it is for sewer lines; not the backflow for water lines which is always required. For the townhomes we manage there is a main sewer line (12'-14' deep). The main line connects to a service line which connects to each of 2 to 8 units per townhome building. The HOA is responsible for the service line and the individual owners are responsible from the common service line into their individual unit. When there is a blockage in the common service line it will flow back into all of the units. If the blockage is in the homeowners individual line the back flow will be only in their unit. There can be several reasons for a blockage, including - tree or vegetation roots; items owners put down their sinks, stools, and drains; and a pipe disconnect or belly caused by the ground movement.

A sewer back flow valve or a check valve is usually placed just outside the unit, before it connects to the service line, to protect against backflow into all openings within the unit. I received an estimate of $1200 to place a backflow valve at an estimated depth of ~2'. Also, a flood guard could be placed in the basement drain (or other lowest access for backflow) at estimated cost of $200; plus a water alarm can be installed to forewarn to call the plumber. I understand the check valve is more foolproof and more expensive than a back flow valve. And if a snake goes through a back flow and is being retrieved the flap will close on it (so the plumber must be forewarned).

So much for my unfortunate education on this subject. I have yet to have actual experience but am afraid it is coming