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Grease traps

Many of the older cities in the Chicagoland area have combined storm and sanitary sewers, meaning that the rain water drainage is collected through the same pipes as the sewage from houses.  This type of system is almost never used anymore when constructing a new system, but many of the older cities still operate this way.

In these older cities with combined sewers it’s very common for houses to have a grease trap built in.  Because the sewer system is combined, and because back when the system was built it couldn’t handle grease very well, grease traps were a way to prevent grease from entering the sewer system.  Here’s a brief description of a grease trap.




A grease trap is a pit buried underground where water from the kitchen drain runs to.  The exit pipe to the sewer is elevated a little bit from the bottom so that there’s always some water in the pit.  There’s a trap built over the sewer pipe, so that grease floating on the surface of the water is held back, but the water is able to run under the trap and out the sewer pipe to the sewer main.  Any solid debris will settle to the bottom.

This way the grease is held back out of the sewer system.  Note that only water from the kitchen flows into the grease trap.  There’s no water from any other sink and certainly no water from any toilet coming into the grease trap.  But there might be water from your gutters flowing into the grease trap.  Where your gutter downspouts go underground they generally empty into the grease trap.

With this arrangement you’ll need to clean out the grease every so often.  This used to be a much bigger issue back when we used a lot more grease in our cooking.  Now you should just throw away your grease rather than putting down your kitchen sink drain.  So how often you need to clean out the grease trap depends on a lot of factors, but it’s likely to be many years (probably a decade or more) before anything will need to be cleaned out.  You can hire somebody to do this for you, or you can just lower a bucket on a rope to scoop out the grease and discard it.

In well over half of the grease traps I see now the trap has completely deteriorated, usually to the point where it’s completely gone.  This isn’t a problem anymore and I don’t recommend that you do anything about it.  There’s just no reason to.  And some grease traps have been bypassed, so that the drainage from the kitchen goes directly to the sewer and doesn’t go into the grease trap at all.

These days the biggest issue with a grease trap is the condition of the ring and the lid.  If the top concrete ring is damaged or the metal lid is broken then somebody could fall through.  But as long as the ring and lid are in good condition then you have very little to worry about with a grease trap.

Sump Pump and Ejector Pump

Many houses have a sump pump, and most newer houses (and some older houses) have an ejector pump.  This blog posts describes the purpose of each of these devices and explains some of the differences.

There’s a lot of water in the ground (of course – that’s why plants have their roots there!) and if any part of a house is below ground then that water wants to try to leak into the house.  And there are a couple of ways to deal with water.

You can try to block water out completely and not allow it to get anywhere it’s not supposed to be.  That’s actually not very easy – water will find a way, especially through an underground foundation that you don’t have access to for maintenance.  Or, you can give water a place to go where it can be controlled and won’t do any harm.  This is the point of a sump pump.

A sump is a pit dug at the lowest point of the house that gives water a place to go and collect before it can come through the foundation wall or through the floor slab.  Usually – but not always – there is also some buried drain pipe (usually called drain tile) running around the perimeter of the house and discharging into the sump.  This drain pipe is perforated so that water in the ground will leak into the pipe and wind up in the sump.

Ground water trying to attack the foundation finds its way into the sump.

At the bottom of the sump is a pump.  When the sump fills with water an automatic valve turns on the pump and pumps that water away, usually discharging outside of the house but sometimes discharging directly into a sewer line inside the house.

So ground water that’s trying to attack your house and ruin your basement instead runs into the sump and is pumped safely away.

An ejector has a completely different purpose.  An ejector deals with drain water from the house’s plumbing system, helping to get it out of the house. In Chicago and most of the older suburbs we have combined storm and sanitary sewers.  These cities use the same large sewer pipes to handle rain water and to handle the drain from your house (from sinks, tubs, showers, and toilets).  Here’s what it looks like, with a typical basement and the sewer line out in the street.  The house’s main plumbing drain pipe leaves through the basement floor, and all the drain water from sinks, toilets, and tubs drain by gravity out to the sewer in the street.

A typical older house with the main plumbing drain pipe going out to the sewer through the basement floor.

It used to be that when it rained very hard in Chicago and some of these older suburbs the sewers became overwhelmed with rain water and actually backed up into the basement through a floor drain.  As you can imagine, this was a huge nuisance and it could do a lot of damage.

During a heavy rain the sewer can get overwhelmed and floor the basement.


So the solution was to start using overhead sewers with an ejector pump.  Now instead of the main plumbing drain pipe going out through the basement floor it goes out through the foundation wall elevated a couple of feet.  All the drain water from the fixtures above this exit point can still drain out by gravity, but all the drain water from the fixtures below has to be pumped up (this includes the floor drain which now empties into the ejector sump).  This drain water first drains into the ejector sump, and when that fills up the ejector pump comes on and pumps this sewage up over a high loop where it can then drain by gravity.  An ejector pump is more powerful than a sump pump, and it’s able to grind up the solid waste from the toilet.

A typical newer home with an ejector pump.

Now if the sewers become overwhelmed by rain water, it would have to back up not just to the floor level but to a point about 6-8 feet above the floor before it could spill into the house.  And if that happens then we’ve all got a lot worse problems to worry about than basement flooding.

Now even if the sewer becomes overwhelmed it’s much harder for that sewer water to back up into the house.

A sump pump just needs a simple cover to keep out debris and to reduce the chance of the water evaporating into the house.  But an ejector deals with sewage – including waste from the toilet.  So the cover to the ejector pit needs to be sealed tightly to prevent those odors from getting into the house, and the pit needs to be vented to the outside through the plumbing system’s existing vent pipes.  So there are two pipes coming from an ejector pit – there’s the drain pipe and there’s the vent pipe.

A sump pump should have a battery backup system so that it can continue to work in case of a power outage.  This is when you’re likely to need your sump pump the most, during a big rain storm that might cause a power outage.  But it’s rare for an ejector pump to have any kind of battery backup system and it’s not really necessary.  But keep in mind that if you don’t have power then you don’t want to use any of the fixtures that drain into the ejector.  You’ll only want to use the fixtures at the first floor and above that still drain directly into the sewer by gravity.

Sediment Trap

A sediment trap is a short piece of gas pipe installed near an appliance that helps to collect debris in the gas line.  The idea is that any debris in the gas line will collect in the sediment trap before that debris can foul up the appliance’s gas valve and cause trouble.

The sediment trap on my water heater is nice and long.

You’ll often hear the term “drip leg” instead of sediment trap.  In fact that’s what I usually call it, but it’s not really the same thing.

A sediment trap is just a T fitting in the gas pipe with a capped pipe nipple at the bottom of the T.  It’s required at a furnace, boiler, and water heater, but not at a clothes dryer, a kitchen range, or a fireplace.

The sediment trap needs to be installed downstream of the appliance’s shutoff valve and as close to the appliance as practical.  And it needs to be installed so that the gas flow changes direction, so that the debris will fall into the trap.  If you install it so that the gas flows horizontally then the debris might just jump over the trap and get into the gas valve.

There’s no excuse for the lack of a sediment trap.  A competent plumber knows it’s required by all relevant codes and by the appliance manufacturer’s instructions.  And you don’t want an incompetent plumber installing your gas pipes.  So if it’s missing that’s one small strike against the plumbing system as we work on telling the story of the house.

But how bad is this problem, really?  Well, I’ve heard that this might have been an issue many years ago, but today the natural gas delivered to your house generally is clean and dry.  And I’ve never personally heard of a problem that occurred because of a missing sediment trap.

So have a sediment trap installed the next time the appliance is replaced.  In the meantime it’ll just be one of the many things in your house that’s not perfect.

Galvanized pipes

Galvanized steel pipes were used for potable water distribution in single family homes as well as in apartment and condominium buildings until about the 1960’s.  It was the standard water pipe material; everybody used it pretty much exclusively.  They’re joined together with threaded fittings.

Galvanized steel pipes are just steel with a zinc coating for protection.  The zinc coating is the “galvanized” part.  But over time the zinc coating wears away, and you’re down to bare steel.  And of course steel rusts.


The inside of this galvanized steel water pipe is corroded.

The pipes will rust on the inside (obviously, since that’s where the water is), and this corrosion tends to clog and choke down the inside diameter of the pipe.  With the smaller inside diameter you’ll get less water flow and lower pressure at your fixtures.  Hot water pipes tend to corrode more quickly, because the heat accelerates the corrosion process.


Reduced water flow and pressure is the predominant problem, but the pipes can also rust through and start to leak.  And of course leaking water pipes can cause a tremendous amount of damage, especially if the leak is inside a wall.  The threads typically rust first, so this is where you want to start looking if you’re going to examine your galvanized pipes.


This pipe rusted all the way through and had to be repaired with a clamp.









The life expectancy of galvanized pipes varies – a lot.  I’ve seen galvanized steel water pipes in houses from the 1920’s and even the 1910’s that are in surprisingly good condition.  The water flow through these pipes is good, and there’s little sign of rusting.  Folks knew how to make pipes back then.  Still, these pipes are very old, certainly have some rust, and are probably near the end of their expected life.  And I’ve seen galvanized pipes from this era that are badly rusted and provide terrible pressure.  You should plan on needing to replace all galvanized pipes in the near future.  Also, most houses of this vintage have had all (or almost all) of their galvanized pipes replaced already.  So if your house still has galvanized pipes then it’s behind the curve in terms of being updated like it needs to be – something to keep in mind when making an offer.


This pipe fitting is rusted through and leaking, just a little bit. The leak will just get worse and worse, until . . . disaster.


On the other hand, some Chicago buildings from the 1950’s and 1960’s have already had to replace their galvanized pipes.  It seems that cheaper production methods and materials created an inferior product that quickly deteriorated.  And I’ve seen pretty much everything between these two extremes.  Either way, if you have galvanized steel water pipes in your house it’s probably near the end of its expected lifespan, and you should plan on needing to replace it in the near future.

Keep in mind that there’s no way to know for sure when galvanized pipes will fail.  You can have a team of scientists and engineers inside your house for a month, and you still can’t know.  You just have to follow the basic guidelines.

In Chicagoland, almost all jurisdictions require new water pipes to be copper.  But some cities will allow PEX (cross linked polyethylene) water pipes.  PEX is used almost exclusively throughout much of the rest of the country, so it has a long record of success, and the problems with fittings (the weak link in any water system) have been worked out by others.