Sewer Smarts and Plumbing Basics

Plumbing within a home and out in our community is critical infrastructure but is often forgotten or misunderstood. Out of sight, out of mind... until something goes wrong, possibly resulting in plugged pipes or flooding.

This webpage is designed to help you understand how the plumbing works in your home, how it connects to City infrastructure, and who is responsible for maintaining various components of the system.

Please note that systems and appliances may vary and not all plumbing is the same. 

Plumbing Connections Prior to 1970s

BeforeHouse_Labels_logoTypically homes constructed prior to 1970 were built with a catch basin type sump pit connecting the foundation drains to the sanitary sewer lateral. Some homes were built with a house trap to protect the house from sewer gases. These traps collect debris and inhibit maintenance of the sanitary sewer lateral. Some homes may also have sump pump discharging directly into the sanitary sewer. 

Plumbing Connections After 1970s

AfterHouse_Labels_logoTypical homes constructed post 1970 consist of foundation drains discharging clear water onto the ground surface away from the house through a sump pump. Plumbing fixtures typically contain their own trap, making whole house traps common in earlier plumbing design unnecessary and cumbersome for maintenance of the system. The "vent stack" or main waste pipe, carries the dirty water from plumbing appliances (such as toilets, sinks, dishwashers, and bathtubs) through the building sewer into the sanitary sewer lateral.

Vent StackHouseStackStack or Waste Pipe

The stack or waste pipe is considered a main wastewater drain line. It collects and distributes wastewater from all those smaller pipes to the main house drain. The Universal Plumbing Code (UPC) defines a "stack" as "the vertical main of a system of soil, waste, or vent piping extending through one or more stories." The stack is the largest vertical pipe into which all the horizontal (and smaller vertical) pipes either drain or vent.

Foundation Drains

FoundatioFoundation Drainsn drains are pipes located under basement walls that collect ground water. They prevent it from damaging your home or anything stored in the basement by preventing water from seeping through the floor or walls of a building. Foundation drains in older homes may connect directly to the private sanitary sewer lateral through a catch basin-type sump pit in the home. They deliver excess groundwater to the sanitary sewer system where it will be unnecessarily treated by a wastewater treatment plant. This clear water does not need to be treated at the wastewater treatment plant and may increase the risk of basement backups during snowmelt and heavy rain events because excess stormwater enters the sanitary system, potentially overloading it and backing up into the basement.

HouseTrapMushroomHouse TrapHouseTrap_VentPipe

Older homes may have a building or house trap (also called a “whole house trap” because it is on the main sewer line). House traps are usually buried in the basement or ground just outside the home, and provides a single liquid seal to stop sewer gases from rising up into the home through plumbing fixture drains. Because new plumbing fixtures contain a trap, these whole-house traps are no longer necessary, can collect debris, limit access for cleaning, and cause flow restrictions in your building’s sewer lines. In Superior, they are prohibited by building code.

The image on the right shows the house trap vent stack pipe on the outside and inside of the house.


Sump Pit, Sump Pump, Discharge Pipe5_clear_water_catch_basin_from_inspection_Meller


  • Called Catch Basin-type Sump Pit – connects foundation drains to sewer lateral (pictured, right).
  • Foundation drains in older houses drain into a catch basin-type sump pit, which connect directly to the private sanitary sewer lateral. Separating the clear water from the sanitary sewer with a sump pump and discharge pipe alleviates the excessive and unnecessary strain on the sanitary sewer system and helps minimize the likelihood and severity of basement backups.


  • Sump Pit with sump pump and discharge pipes
    • Sump pit is a hole with a gravel base dug into the lowest part of a home. Water flows into the sump pit from foundation drains.
    • Sump Pump
      • A sump pump is a submersible pump used to pump clear water that has accumulated in the sump pit out through a discharge pipe to a yard or stormwater structure.
      • A sump pump is a small pump installed in a sump pit, at the lowest part of a basement. Water flows into the sump pit through foundation drains. A sump pump will help keep the area under the building dry and reduce the chance of flooding during rain events.

SumpPumpDischargeSump Pump Discharge Pipe

Discharge pipes direct clear water from the sump pit to ground surface away from your home. 

If a flexible, corrugated sump pump hose is connected to your sump pump discharge pipe to get the water away from your foundation, it must be disconnected during the winter months to prevent freezing and seizure of the sump pump. 

Disconnect the flexible sump pump hose each Fall when you are doing your lawn clean-up and putting your garden hose away. Reconnect the hose in the Spring.     

The flexible sump pump hose is supplied with a rubber coupling and two hose clamps. A standard screw driver is needed to attach the flexible sump pump hose to the PVC discharge piping.

Sump Pump Maintenance

Since the sump pump usually does not operate over the winter months, it is a good idea to run it manually once prior to snow melt. To do this unbolt the cover (if necessary) and pour enough water in the pit until the float lifts up and starts the pump. You should hear the pump turn on. 

If you have poured water and it is over the top of the pump and the pump is still not functioning, this could be for a few reasons: The float could be stuck, the outlet or breaker could be tripped, or the pump may need replacement. Reach inside the pit and try to lift the float. If the pump turns on, the float had likely built up some sludge from the stagnant water. Try pouring more water into the pit to make sure the sump pump is working properly now. Otherwise, check the outlet reset button or electrical panel for a tripped breaker. If the breaker isn’t tripped, you may need a new sump pump.  

Click for more information about maintaining your sump pump.

SewerCleanOut_LabelsSewer Cleanout3_cleanout_on_stack_from_inspection_Pearson

  • A sewer clean-out is an accessible opening, or cap, in your home’s sewer line which allows for maintenance of the private sewer system. Clean-outs are oftenClean-out found in the basement on the floor, sewer stack, or outside the home along the private sewer lateral.

floor drainFloor Drain

A floor drain is a plumbing fixture designed to remove possible standing water in the floor of a structure. It typically consists of a drain grate (cover) in rectangular or round shape, sediment bucket (trap), a p-trap under the drain, and backwater valve in addition to the drain pipe itself.

To prevent sewer gases from coming up through the drain, add a half a gallon of water to your floor drain at least once a month. At least once each quarter, check your drains for debris and clear them.

2_in_field_backwater_valve_pic_olsonBackwater Valve

Backwater Valves reduce the likelihood of sewage backing up into your home. A properly maintained backwater valve allows water to flow only in one direction at a time due to a mechanical disc (flapper) that will close during high flow periods (i.e. large rain events), reducing the chance that sewage can enter your basement from the City sewer main. A backwater valve is installed in the private sewer lateral (the line that connects your home to the city sewer).  

The Backwater Valve should be inspected and cleaned as needed at leaBackwaterValvest twice per year. Maintain your Backwater Valve during dry weather. Sewer gases may be present, be sure to use adequate ventilation. Be sure no one is using the plumbing facilities in your residence when you open the Backwater Valve.

Click for more information on maintaining your backwater valve.

GrinderPumpIllustrationGrinder Pump

A grinder pump is placed in a tank (or well) that is buried in a convenient outdoor location on a homeowner’s property (grinder pump units also can be purchased for inside installation). The tank provides wastewater holding storage capacity. When water is used in the house, wastewater flows into the tank. When the wastewater in the tank reaches a pre-set level, the grinder pump automatically turns on, grinds the waste, and pumps it out of the tank via the homeowner’s on-site sewer service line and into the public sewer system. A grinder pump will normally run for one or two minutes and automatically turn off when the tank is emptied. The pump is powered by electricity and is connected to a control panel near your electric meter.

In most instances, wastewater flows by gravity from a home/business’ on-property sewer service line to a public sewer main where it travels to wastewater treatment plants. At the plants, the wastewater is cleaned, disinfected and safely returned to the environment. However, because of elevation, gravity may not work in all instances. In situations where a home/business’ sewer service line leaves the building at a lower elevation than the public sewer main, a grinder pump is sometimes used to grind and pump wastewater to the main.

Household Plumbing

Plumbing within the house may include the following appliances, all of have a "plumbing trap" and are connected to a vent stack or main waste pipe which flows out to the sewer lateral and the sanitary system.

By definition, a plumbing trap is a device that keeps a small amount of liquid every time the fixtures is used. The amount of retained liquid is called a trap seal. This trap seal prevents sewage system odors, gases, and vermin (mice, insects, etc.) from entering the living or work space.

Trap seal is the maximum vertical depth of liquid that a trap will retain measured from the crown weir and the top of the dip of the trap. The most common of all plumbing traps is the p-trap. This is used with kitchen sinks, lavatories, and laundry sinks.


2in1Toilet_LabelsLeaky Toilets

  • Misadjusted flush valve assembly – If the leak is in the interior of your toilet (your toilet runs constantly or makes a dripping noise) there could be a problem with its flush valve assembly. Often times this will cause water to enter the overflow valve and continuously fill up in your tank. 
  • Worn out flapper – Another common cause of an internal toilet leak is a worn out flapper. The flapper blocks water in the tank from entering the bowl, and if that part is worn out it will cause water to continuously leak into your bowl.
  • Problems with the Fill Valve – This is one of the most common toilet issues.  When you have a faulty fill valve, you will hear water running continuously, or the toilet may not even flush at all. Even if you don’t hear the water running, it’s important to know that sometimes, minor leaks in toilets go unnoticed. The best way to determine a leak due to a faulty valve is to pour some food coloring into your toilet tank to see if the water in the bowl turns the same color. 


Flexible supply tubes carry water from shutoff valves at the wall to threaded tailpieces on the base of the faucet.  The drainpipe that runs through a bathroom sink usually is fitted with a pop-up stopper that raises and lowers when you pull up or push down on a knob or handle just behind the faucet body.  The knob is actually the head of a lift rod fastened to a flat, slotted bar called a “clevis”, which is a connecting bar.  The clevis connects to a rod that runs through a rubber pivot ball and slopes slightly uphill to the tailpiece of the stopper.  

Pushing the knob and the lift rod down causes the pivot rod to push the stopper up; pulling the knob up causes the pivot rod to pull the stopper down.  If you want to remove the assembly, you may be able to pull it right out or you may have to twist it to unhook it from the clevis.

The tailpiece, which may be fitted to a pop-up stopper, attaches to a drain trap by means of slip-joint couplings.  A sink trap remains filled with water so that sewer gases can’t enter the room.  

A mechanical pop-up stopper is operated by a system of levers and rods.  If this isn’t working properly, the solution is usually just a matter of adjusting the clevis screw or the position of the pivot rod.  


Bathtub have two drains, one to the main drain opening and the other to the overflow drain opening.  To close and open the drain, two different assemblies are common:  pop-up and plunger-type.  Both are operated by a trip lever at the overflow drain.  

With a pop-up drain, linkage forces the drain stopper up or down by way of a rocker arm.  With the plunger type, a hollow brass plunger slides up and down inside the drain assembly to seal the drain opening.  

The overflow pipe is designed to stop water from spilling out if someone accidentally leaves the faucet on or overfills the tub before getting in.  

A bathtub trap remains filled with water so that sewer gases can’t enter the room. 

Stormwater Flood Control Program

If you live in a single-family, residential home in the City of Superior and have experience basement flooding, consider signing up for the City of Superior Stormwater Flood Control Program. The SFCP provides financial assistance to homeowners looking to reduce basement backups by updating plumbing. More information and online submissions form can be found here: