Private Well and Septic System After a Flood

How does floodwater affect a private well?

Floodwater is surface water carrying bacteria, viruses, chemicals and sediment. If it reaches the pump, the intake, or the water table, it contaminates the well. Once a well is flooded it must be disinfected and tested before it is safe to drink, and testing is arranged through your local board of health.

A well pump sits in a drilled or dug hole, often 20 to 100 feet down. The hole itself is cased, but the casing has a hole at the bottom and side holes through which water enters the system. If the water table rises above the pump intake - which it does in a major flood - water from the surrounding soil and surface runoff enters the system along with whatever contamination those waters carry.

A flooded cellar can also reach a pump intake if the pump is in the cellar itself, which is common in older systems. The pump then draws water from the standing flood, carrying all of its contents into the house supply.

The rule is simple: if floodwater reached the pump, the intake, or the ground around the well head, the well is contaminated. Turbidity - cloudiness from sediment - is visible, but bacteria and viruses are not, and chemical contaminants are invisible. The only safe answer is disinfection and testing by someone qualified to do it.

A well that is not flooded - that sits on a hill or is far enough from flood sources - usually comes through a heavy rain unaffected. But in a river valley or a low area where the water table rises, every flood is a test.

How does floodwater affect a septic system?

A septic tank holds waste and separates solids from liquids; the liquid drains to a leach field. If flood water covers the tank it pushes sludge up and out, clogs the lines and can break the tank. If groundwater rises, the system cannot drain, waste backs up into the house and leaks out of the field.

The septic tank itself is buried - usually 1 to 3 feet deep and 4 feet below grade at the inlet. If floodwater rises above the tank it floats or cracks, and pushes accumulated solids up and out into the leach field, where they ruin the soil's ability to filter water. Water sitting in and above the leach field prevents it from draining and turns the system into a surface discharge.

A broken tank or a flooded system is also a public health and environmental hazard, because waste is reaching groundwater without the treatment the soil was designed to provide. Your local board of health is involved in confirming the damage and approving the repair.

The diagnosis is straightforward: if you know or can see that floodwater reached the tank or the leach field, the system was compromised. A backed-up toilet, ponding over the field, or sewage odours around the tank after a flood all confirm it. Call the board of health and a septic pumper or installer. The board says what needs to happen next, and they verify it was done.

What is the first step if a well or septic was flooded?

Call your local board of health. They set the rules for testing and operation, and they are the authority on what your system needs. In a small town they may handle it directly; in a larger one they guide you to a certified lab for well testing or a licensed pumper for the septic.

Do not use the well or flush the toilet into a flooded septic system - that spreads contamination. Do not let a pumper bypass the board of health's review. After the board has assessed the damage they will tell you whether the system can be disinfected and reused or must be replaced, and they will specify any testing that must be done before the system is back in service.

For a well, disinfection is usually chlorination, followed by flushing and laboratory testing for bacteria and nitrates. The board tells you how many days to wait between disinfection and testing, and what lab to use; many boards have a preferred list of certified laboratories.

For a septic, pumping usually comes first to remove the flooded contents and break the sludge layer that was disturbed. Inspection with a camera confirms the tank and outlet pipe are sound, and then pumping and inspection of the leach field follows. If the field is damaged the board decides whether it can be cleaned and restored or must be replaced.

• Call the local board of health immediately after a flood.
• Do not use the well or flush into the septic until the board and the testing lab clear them.
• Have the well disinfected and tested by a certified lab on the board's schedule.
• Have the septic pumped, inspected by camera and the leach field assessed.
• Get written confirmation from the board that the system is back in service.

Where are private wells and septic systems common in this area?

Municipal sewer serves Baldwinville and parts of the surrounding towns through the Baldwinville-Otter River Sewer District. Private wells and septic systems are common in the villages beyond that district, and they are the norm in rural areas and in the outlying towns of Hubbardston, Petersham, Ashburnham and the hill towns.

The Baldwinville-Otter River Sewer District was created by special act in 1965 and the treatment plant on Reservoir Road discharges to the Otter River. Some homes in Baldwinville are connected to it; others are on private septic and draw from wells or from a private Light and Water operation in the village. East Templeton, Templeton Center and Otter River village are the other places in town, and each has its own pattern that the local board of health keeps track of.

The outlying towns - Gardner, Winchendon, Athol, Orange and beyond - have a mix. Some have municipal sewer and water in a dense centre and nothing beyond, leaving rural households on wells and septic. Others have no municipal systems at all. A house that relies on a well and septic is responsible for maintaining both, and the cost of maintaining them in a flood-prone area includes recovery from floods.

In the New Hampshire towns - Rindge, Fitzwilliam and New Ipswich - every house effectively relies on a private well and septic because there is no municipal sewer. The local health officer, not a board of health, oversees the systems and sets testing and repair rules.

What testing is required after a flooded well?

The local board of health specifies the testing. Standard tests include bacterial contamination (E. coli and total coliforms), nitrates, and sometimes turbidity and pH. Testing is done by a certified laboratory and costs some tens of dollars per test. The board tells you which lab to use and when to test.

A well disinfected with bleach must sit for a specified time - usually 24 to 48 hours - before samples are taken, so the test takes place several days after the flood. You cannot use the well for drinking, cooking or ice-making until it passes. Showers and toilet use are usually allowed after disinfection while waiting for results.

If testing fails - if bacteria or nitrates are above the limit - the board decides what comes next. Sometimes a second disinfection and retest solves it. Sometimes a filter or a treatment system is needed. In a few cases the well cannot be repaired and a new well or a connection to municipal water is the answer.

The test results are yours and the board's; they are required for a home sale under Massachusetts law (a Title 5 inspection is required when a property with a septic system is transferred or enlarged), so keep them.

What does a septic repair or replacement look like?

Pumping and inspection are diagnostic. If the tank is cracked or the outlet pipe is damaged, replacement is the answer. If the leach field is flooded and cannot drain, it may be cleaned and restored with the board's approval, or a new field may have to be installed in another part of the yard.

A licensed septic contractor diagnoses the problem, quotes the work and gets the board's approval before starting. The work requires a permit from the town because it involves excavation and below-grade construction. The board inspects the work before the permit is final.

A new septic system - tank, leach field, and all the plumbing connecting them - can easily cost several thousand dollars. If a flood is a regular risk, investment in protecting the system - elevation, a solid cover, perimeter drainage to route floodwater away - might be less expensive than repeating a flood repair every few years.

Some properties are in flood zones; others simply sit in a low spot and have flooded once in living memory. Understanding your own risk is the first step. FEMA's Map Service Center shows what flood zone you are in, and the local board of health can tell you about past flooding in your area.

Can you use the well or septic while repairs are happening?

During work, no - the contractor will tell you what is shut off and for how long. After disinfection of a well, usually not until testing passes. With a septic repair, it depends on what is being done; the board specifies what can be used and when.

A well being disinfected and flushed is shut to the house, which means no water pressure. Alternative water is usually a bottled supply for drinking and cooking, and sometimes for flushing if the septic is also in question. A small flood in a single-family home is usually repaired in days; a larger system or a multi-family building may take longer.

A septic repair that involves the tank means the system is shut down for the duration - no flushing. Porta-potties are often set up on site. Repairs usually take a week or two, and the final board inspection can take a few days to schedule. The board inspection clears the system for use.

Until everything is done and approved, you are without normal water and sewer, which is why time and communication with the contractor matter. Ask for an honest timeline at the start.

What role does the local board of health play?

The local board of health is the authority for testing requirements, safety standards, and repair approval. They may do the testing, inspect the well or septic, or guide you to a contractor or laboratory. If there is a dispute, they decide.

Each town has its own board of health, made up of local appointed members with public health training and legal authority. They set rules that comply with state law, and they also handle complaints and enforcement. If you are unsure what your system needs, the board's office is the place to start.

In Massachusetts, the Title 5 inspection is a specific kind of septic inspection done when a property changes ownership or is enlarged. It covers the tank and the leach field, and the results go to the board. A flooded septic inspection is different - it assesses damage and what repair is needed - but the board oversees both.

The board of health also issues a permit for any septic or well work, and they inspect the finished repair before it is approved. They are your path to a licensed contractor and a certified lab.