Septic System Question


Hi everyone, I am looking at a park that is on septic. I was told there are individual tanks for each lot or in some cases, tanks that serve two lots. Will there be individual leach fields for each lot? The park is relatively flat so without a lift station, not sure how you could funnel all of the waste to a common, shared leach field.

What should I worry about with a system of this type? Why would it have been set up this way to begin with?


Could be a common drainfield but most likely each tank has its own drainfield. This is a pretty common set up in mobile home park land. Downside lots of tanks to pump every year. Upside non common drainfield to fail i.e risk diversified. Due diligence will be expensive to inspect each tank and drainfield but that is just life. Main concern is you must a have a replacement area for every drainfield.


That’s helpful, thanks. How big would you expect a field to be for a tank that supports one home? There is a wide strip of land behind the homes where I suspect the fields are located. Trying to gauge the likelihood that there is enough land to put a new field in. What would you expect it to cost to replace a tank, a few $k?


Drainfield size depends on soil characteristics. 100 to 300 linear feet usually in multiple lines. 1000 to 1500 gallon tank $2000 plus installation


Thanks Phillip! So how much including installation? Are there any issues with inspecting tanks in the winter?

Other than what I’ve mentioned, are there any physical items I should be considering/asking about? The owners install and maintain septic systems outside of their ownership of the parks, among other things, so I’m optimistic that they’ve been well-maintained.


Tank installation: get a permit $300 to $1000, dig a hole put tank in hole, water test tank for leaks half a day to full day @ $500 to $1000. Come back next day plumb tank in, Fill old tank with sand another 1/2 day two full day @ $500 to $1000. Thats my total best guess estimate labor and permits.

Since owner is spetic guy he should have good as built maps and all permit history, and pump history for the park


@PhillipMerrill What do you think about when switching to a new drain field to install a value that can redirect to the old field again if the new field fails?


Its a good idea. Whether it will work or not depends on why the old one failed. Drainfields fail for alot of reasons: plugged by fat, grease, or, sludge blown out of tank due to lack of pumping, overgrowth of biomass reducing permeability, roots, high water table (maybe seasonally high), compaction, soil was never really that permeable to begin with (clay). The only two or three that may allow you to bring an old back one online are biomass overgrowth, poor soil permeability, seasonal high water table. The best way to go would be to alternate between both drainfields with a pump and timer. Field 1 would get first dose say at 7am, field 2 next dose at 8am then back and forth all day. If there is long periods say more than a day or two between doses the microbes will starve to death. They will regrow but it takes a couple of weeks to a month. No microbes no treatment of the waste water. The drainfield is not just about disposal its where the majority of the treatment takes place.

Sorry for the long answer


Knowing that the microbes die, do new systems require theses bacteria to be added to get their numbers high enough to be reasonably effective? This leads into what happens when bringing in new homes to fill lots with septic and bringing in new tenants to empty homes in general. No wonder people avoid private utilities.


Bacteria and microbes are naturally occuring (environment and in human waste). In a new system it will take weeks to months to fully colonize the substrate. In package plants (activated sludge) to start a plant maybe 1500 to 3000 gallons of sludge ( microbes) are brought in and used to “seed” it with microbes. Very rare and not necessary to seed other types of systems