Michael H. Levin, Ph.D., F.A.A.A.S.

Backwater flow valves are already on the agenda at Haverford Commissioners work meetings. The commissioners may have the 5-votes necessary to require the device in order to keep sewer water out of houses and vote to pass it as a Haverford ordinance at a regular commissioners meeting.

DELCORA, the Delaware County Regional Water Quality Authority, has recommended this to municipalities of Delaware County because of more and greater precipitation as well as illegal inflow from storms and sump pumps in the present era of climate change.  A cursory review shows ~5 municipalities in Pennsylvania have some type of ordinance mentioning testing and/or backwater preventer device and inspections of sanitary sewer laterals; Haverford is not yet one of these, although new properties* (see below) are required to have them.

The purpose of this presentation is to illustrate how these backflow preventers would create costs of both installation and maintenance for home or business owners and whether these devices would work as is believed, the costs involved as well as whether improvements in homeownership would ensue.

A plumber who was present at the last Commissioners workshop meeting was queried and his shop visited to view devices that he brought along with him to the commissioners work meeting in a “show and tell’ presentation. One of the backflow preventers installed in the sewer line is under spring tension it is considered unacceptable; springs wear out. Others are approved by the International Plumbing Code; even so, the water gates (flapper gates) are thinner than a pencil and points of flapper gate attachment are flimsy for a durable device supposedly designed for a lifetime of trouble free operation.

The plumber offered an “off-the-top-of-his-head” estimate for installing an approved plastic model as $2,500 - $3,000 . . . and up, essentially, in a “one-size-fits-all” type of installation; I am certain that he won’t be held to these figures; it could be higher, considerably more. The devices the plumber showed were similar, but not the same as those shown in the website below which have additional features; some are deluxe models. There are various styles, as well as add-ons such as simple electronic devices that reassure the homeowner that the device is working. All backflow preventers require maintenance as DELCORA points out.  This means frequent maintenance; another tier of responsibility to prevent device failure to operate,

The website below is a fairly comprehensive view of the products that may be purchased with agreement between you and your registered plumber who would be required to sign-off on the installation of  backflow preventers and associated devices.


Backwater preventers or valves incorporate a single working principle: a swinging flapper-like gate that permits wastewater to flow in one direction out of the house but closes if wastewater begins to flow back in as the result of increased hydrostatic pressure from water in sewer mains and laterals in the street as might occur in an overloaded system.  Once installed, the backwater preventer doesn’t necessarily ensure that wastewater won’t flow back into the house. Intermittent use of a backwater preventer, however, might prevent waste backwater from entering the house for long periods, say months or years.  Then, with flooding of a sanitary sewer, the main valve would be expected to operate flawlessly to prevent any intrusion of wastewater into the home.  Few devices such as this are expected to operate flawlessly under such conditions, e.g. sump pumps are one of these which may fail to operate when needed.  The backwater preventer may also fail due to plugging with debris in the sewer line, failure of the backflow preventer gate itself by a jam or breakage.  Overall, a 4″ sewer line in a home probably is not open the full 4″; much waste sticks to the inside of the sewer pipe.  Frequent cleaning of the sewer pipe is not a good idea; it is accepted plumbing practice not to clean a sewer pipe unless it is clogged and that may damage the sewer pipe. Cleaning a sewer pipe, with a backwater preventer installed is really asking for clogging as well as damage to the pipe requiring replacement; costly expenses could ensue.

If the commissioners approve such an ordinance for backwater preventer valves, it would apply both to new and existing homes that meet criteria selected;  briefly, these are: open floor drains, toilets, etc., less than 22″ (or maybe 24″, greater is better) above the nearest manhole cover over a sanitary sewer water carrying water from a lateral to a main from a residence . . . and preferably not back into it.  At least a 2% drop in the home sewer lateral line is necessary for the backwater valve to operate at the point of installation, for the backwater preventer’s gate to smoothly open and close. The backwater preventer may be installed either in the residence at a wall or outside the house in the ground.  Water flows downhill; it will do so even for a 1/16″ drop in elevation, but more of a drop is necessary to assuredly open and close a backwater valve.

The backwater preventer would probably have to be installed within 90 days of sale.  No home “Occupancy Permit” would be issued until the backwater valve is installed.  Cleaning, televising, and imaging the sewer line prior to installation of the backwater valve would be necessary with a local municipal inspector present at the time; defective, cracked or broken sewer lines would have to be replaced if found or as requested.  Again, frequent checks on the valve operation are recommended and necessary to determine whether the backwater device is in working order.  Spare parts on hand are also recommended; this backwater device is no perpetual motion machine.  Very limited equipment warranties are offered either by the backwater preventer manufacturers or the plumbers who install them.

Summary.  The installation cost of a new backwater preventer valve required by a municipality under its ordinance is neither covered by a homeowner’s master insurance policy nor an add-on policy offered by Aqua through its business partner, Home Serve.  Replacement of an existing backwater preventer valve is covered up to an amount specified in the policy.  Read all of your homeowner policies for applicability to flooding and a backwater valve placed in a sewer line; there are more exceptions and exclusions that might stop you from making a successful claim in the event the backwater preventer fails.

A Word To The Wise. Back-up even low deductible insurance policies with distinct and separate inexpensive ones such as offered by HomeServe for: (1) interior house plumbing, and (2) outside the home connector sewer pipe from house to the main sewer line. Remember, sewer lines clog and break.  Flow channels shrink the size of the open channel through which water flows with regular household use.

Cleanout sewer pipes only when necessary.  Excessive cleanouts are harsh steps even when necessary, and may render sewer pipes unusable requiring extensive and costly sewer pipe replacements which may be beyond any insurance coverage which is limited by a lower dollar amount.

What should Haverford Township do to prevent sanitary sewers from back-flooding into properties?

Haverford Township should identify the communities where sanitary sewer flooding is either known to have occurred or is expected to occur.  Take such corrective steps as are necessary including Town Planning with long-range vision. Map the sewer systems with their type,age and diameters.

Ensure that water from stormsewers does not flow as inflow into sanitary sewers.

Retain a sanitary engineer for input into the overall community planning process.

Think through the calculus of disruptions to plumbing services, excavations and associated messes of numerous homes in the throes of pipeline renewals.

Backwater flow preventer NO092015.BC.doc