Family Owned - Serving The Tri-State Area Since 1967!

Wet Basement Problems

Wet basements …what a mess!

Wet basement with lots of dark mold spreading on walls, doors, and belongings
Nothing is more frustrating than dealing with a wet basement. It can damage walls and flooring and ruin personal property items such as irreplaceable photo albums and family heirlooms. Insurance coverage for wet basements varies from state to state and company to company. But typically, the damage from water seeping in from the outside or backing up from the sewer is not covered by standard homeowner policies. In some cases, special coverage can be purchased to cover these risks, but it is usually limited in the types of personal property it covers and amounts of coverage that may be purchased.

It is up to each homeowner to know how to prevent water damage before it starts. This can be done through proper home maintenance and installation of systems intended to remove water before it gets into the basement.

This article will explain:

In order to prevent wet basements, it is important to understand where the water is coming from. There are four common sources of water that seeps into basements (See Figure 1: Common Sources of Basement Water Seepage):

Common sources of basement water seepage

Basement water problems are often unpredictable. A home may have had a dry basement for years, but start to have water seepage problems during a wet spring, even though the wet weather is not the worst that the house has seen in the past. Area development may cause groundwater levels to rise, may increase storm water runoff and overload storm sewer systems, or affect underground springs. The waterproofing on the exterior side of the basement walls may have developed cracks due to house settlement. Tree roots may have damaged and blocked the underground drain tile. Or, it could be as simple as forgetting to clean out the gutters.

When homeowners experience wet basements for the first time, it is imperative to determine if the water problems are going to reoccur or was it a one-time event. Essential to solving this question is determining where the water is coming from.

Controlling Surface Water

If this is the first time for basement water problems, the first thing to check for is the possibility that large quantities of surface water are draining down next to the foundations. Water coming in at one location and only at the exterior foundation wall are typical indications of surface water problems. Here are some things to look for:

If any of these problems are found please contact 3 Brothers Waterproofing immediately correct them.

Controlling Subsurface Groundwater Under Hydrostatic Pressure

If no surface water sources are found, then the source of the water is likely subsurface groundwater under hydrostatic pressure. Unfortunately, subsurface groundwater problems are more difficult and more expensive to fix than surface groundwater problems.

When the groundwater levels outside the basement rises above the level of the floor, the basement acts like a boat in a pond. If a boat is sitting in water, water will leak in through any open cracks or holes. It works the same way with a basement. A basement is not built as watertight as a boat. Hydrostatic pressure can push water through hairline cracks.

Symptoms that point to subsurface groundwater under hydrostatic pressure are water coming up through cracks in the basement concrete floor or water coming in at multiple locations.

If you have an older house within town and the house has a basement with no sump pump, it is likely the perimeter foundation drain system connects directly into the city storm sewer system. If the level of the basement is below the street level, there is the potential of storm water backing up in the city storm sewer system and being pushed into the perimeter foundation drain system. This can saturate the soils around the house at the basement level with storm water under hydrostatic pressure, causing water to leak in.

Another source of subsurface groundwater is an underground spring.

No matter where it is coming from, there are two primary methods of controlling subsurface groundwater.

Installing waterproofing on exterior walls is probably not going to take care of the problem. Hydrostatic pressure can force water up from below the floor slab where it is impossible to install waterproofing after the slab is in place. Installing waterproofing on the exterior side of the foundation walls is expensive too. The earth must be dug away from the wall, then the waterproofing applied, and the earth filled back in. Any future movement in the foundations may open cracks in the wall that the waterproofing cannot bridge, allowing water to enter.

What is more typical is to install some type of perimeter drain system. The intent of the perimeter drain system is to relieve the hydrostatic pressure. The groundwater is pushed into the drain system and not into areas where it can damage carpets, walls, or belongings. The water drains by gravity into a sump pit where a sump pump discharges it out of the house.

There are two basic types of drain systems for wet basements. One is a perimeter above-slab gutter system installed at the base of the exterior foundation walls on top of the floor slab. It doubles as a base material for the wall. The other type of drainage system is a below slab perimeter drainage system. The below slab system requires the partial removal of the concrete floor slab and installation of drainage pipe making it more expensive than the base gutter system (See Figure 2: Common Types of Basement Drain Systems):

Common Types of Basement Drain Systems

Unfortunately, there are no published studies on the effectiveness of these systems. Nor are there studies on which type of system works best. Because effectiveness has not been historically measured, decisions must be based on what is believed to make the most sense.

It is believed that an underfloor drainage system is better than an above slab gutter system. This is because the underfloor drains are believed to relieve the hydrostatic pressure before the water reaches the bottom of the floor slab. If the drain pipe can be placed as low as possible without being placed below the bottom of the footing, it is assumed this is the best location (See Figure 3: Perimeter Basement Drain System):

Perimeter Basement Drain System

The perimeter drain pipe can be placed around the entire building or a portion of the structure. Runs of drain pipe also can be placed below the middle of the basement floor slab to relieve hydrostatic pressure under the middle of the floor. The decision on how much drain pipe to install and where to install it is usually based on the past experience of the installer based on the magnitude of the basement water problem.

An important component of a perimeter drain system is the sump pump. If the sump pump fails to work during a heavy downpour, water could leak into the basement. Please contact 3 Brothers Waterproofing to install a sump pump.

Storm Water from the City Storm Water System Backing Up Into House

In many older houses with basements (mostly pre-1980), there is a perimeter foundation drain outside the exterior wall, at the level of the basement floor, next to the footings at the time the house was built. A pipe was usually installed from the perimeter foundation drain to the street where it was connected to the city storm sewer system.

This can become a problem as the city storm sewer system becomes inadequately sized as more development causes more rain runoff. When this happens, the rainwater in the sewer system can get so high that water flows backwards toward the house. The perimeter foundation drain fills with water and releases large quantities of water into the soil next to the footing and basement floor.

The soil becomes water-logged and the water which is under hydrostatic pressure leaks into the basement. This is a common problem and many cities have outlawed the practice of connecting perimeter foundation drains to the city storm sewer system.

What should you do if you have this situation? Usually the installation of an interior perimeter basement drain system connected to a sump pump will take care of the problem. The interior perimeter basement drain system can usually pump the water out and onto the ground as fast as the water is backing up from the city storm sewer system.

If that doesn’t take care of it, the other, more expensive alternative would be to dig up and cap the pipe that is running from the house to the street from the perimeter foundation drain. However, this is not always possible because many times, this pipe is also draining sanitary waste from toilets and sinks in the house.

If you believe you have this problem, contact 3 Brothers Waterproofing for help.

Sanitary Sewer Water from Municipal Sewer System Backing Up Into House

If the water is coming up through floor drains or sink drains in the basement, then the problem is likely water backing up from the municipal sanitary sewer system. This usually occurs in older sections of some cities that have combined sanitary and storm sewer systems. During heavy rains, combined sewer systems can become overwhelmed with water. This can cause sewer water to back up in the system and sometimes into homes.

This creates a mess for most homeowners because it usually means they are getting other people’s fecal waste backing up into their basement. To correct this, cities should update their sewer systems so the sanitary sewer and storm sewer are running in separate pipes. Until this work is complete, the homeowner can install backflow preventers that help stop sewer water from flowing backward into the house.

Unfortunately, because the city sanitary system works in conjunction with every house sanitary piping, the backflow preventer usually cannot be located on the house’s main sewer line. It usually requires several backflow preventers at all basement drain locations, such at every floor drain, every sink, and every toilet.

These backflow preventers require routine maintenance to make sure they are kept free of debris.


Water in the basement is one of the most frustrating problems a homeowner can face. Most homeowner insurance policies do not cover water damage from groundwater seepage or sewer back-up. Some insurance companies offer special coverage for this type of damage, but the type of items that are covered is usually very limited.

Because much of the cost to replace damaged items and clean up the mess is not typically covered by insurance or limited in coverage, much of the financial burden falls on the homeowner. Being prepared can help prevent these types of water problems.

If your house has had any basement water problems in the past, don’t risk further problems by not doing something about it. Assess your situation and contact 3 Brothers Waterproofing to take the proper steps to keep it from happening again.