Cesspool vs Septic system, what's the difference?

Question

I own a home on Long Island, NY, which has an original block construction cesspool. These are known to collapse, and I'd like to replace it in the near future. I was given two options for replacement:

1. A septic tank system
2. A replacement cesspool - this is made of 3 stacked concrete rings, with a dome top. Works the same way as the current cesspool, but is not supposed to have the same danger of collapse.

The septic tank system is about $2000 more than the cesspool system.

Has anyone had to go through this and can tell me the pros and cons of each? I'm not sure if spending the extra money is worth it. The terms "cesspool" and "septic" seem to be used interchangeably or maybe incorrectly, I'm having a hard time finding info.

The septic system is supposed to be pumped every 3 years, the cesspool system has no pumping schedule, I assume you just let it go until it backs up...?

Thanks

Answer 1

A septic tank has a leach field , a cesspool or the one my grandfather had was a tank that drained into the soil. Garbage disposals and high soap / cleaners flushed or in the wash water are things that plug up both systems, if the bacteria can't digest the waste or is killed off from high concentrations of chemicals etc both will fill and fail. My grandfather's was always a place you did not want to be when the wind was going the wrong way, never have that problem with a septic tank. But modern ones may discharge differently, I know cesspools are not allowed in that area unless you have 20 acre lot or larger.

Answer 2

They are different. The primary difference is that a cesspool is a relatively small and shallow sludge tank, perhaps feeding excess water into a "dry well" for percolation. A septic system has a water-tight sludge tank (sized for the purpose) and may have an expansive network of downstream pipes in the "leach field", according to local soil conditions and other system design parameters.

A cesspool may be illegal in some places and can be dangerous if not properly maintained. I have seen a person crash through a decayed cesspool cover as he walked in the snow in the back yard of an old home. A cesspool is also much more likely to be breached during a surface flooding event, spreading the contents into the neighboring yards and streets...

There are many other variables, including the slope and proximity to wells used for fresh water. In many cases a septic leach field may be located uphill from a septic tank, where electric sewage pumps are used, and have the necessary backup provisions. One-page overview of septic and cesspool systems

Answer 3

To me, a cesspool does not have a drainfield and allows sewage to “seep” into the soil. A septic tank does not have holes. Rather it holds sewage until the solids (toilet paper, etc.) settle to the bottom of the tank and only liquid flows out of the tank and into the drainfield.

Obviously, the drainfield system will last longer, because most of the solids remain in the bottom of the tank and will often decompose...then flow out into the drainfield.

The size of the drainfield depends on 1) type of soil, 2) slope of site, and 3) how often the wind blows., and 4) size of tank.

1) Granular soil is better than clay. They’ll do a percolation test on a sample of soil.

2) A sloping site could require a switch back layout, and solid pipe is used on the sloping portions and perforated pipe is laid flat. Yep, it’s laid flat because you want the liquid sewage to flow evenly to the entire system.

3) Little known fact: liquid in the pipe flows into the gravel (which is in the trench around the pipe) and the wind blowing across the site (and average outdoor temperature) will help the moisture evaporate. The depth of the pipe and amount of gravel (1’ wide trench or 2’ wide trench) around the pipe is critical to the efficiency of the system.

4) Bigger tanks will allow the sewage to decompose longer before getting pushed out into the drainfield. A drainfield works on the principle of water flowing out of the tank every time you flush the toilet or take a shower and send more liquid into the tank. Having a bigger tank allows everything to decompose longer. Having a “healthy tank” like @Ed Beal says means allowing the microbes in the tank to eat the solids. Too much laundry detergent, kills the bugs. That’s bad for your system. (You can buy power to counteract detergent and flush it down the toilet each month. Then it stays health and you won’t need to pump the tank...ever.

Your local Environmental Protection Agency (EPA) or Department of Environmental Quality (DEQ) will determine the design and length of drainfield. (By the way, it can’t be too close to a property line or too close to a well.)

The size of the septic tank and length of drainfield will determine how many bedrooms you can have. (They don’t care about how many bathrooms, the number of occupants determines the impact on the system and that is determined by the number of bedrooms. So, if you have a 2 bedroom house and want a 3 bedroom, move a bed into that storage room, or basement area before they come out to your house. They can’t reduce the number of bedrooms, but they can prohibit adding bedrooms.