# Understanding Septic - Tank Size



## Ditchmonkey (Mar 19, 2015)

I have an old steel 500 gallon septic tank that is in bad shape. I'm going to need a bigger one when I replace it to comply with current codes. My question is, what exactly do you gain with a larger tank? Using the following article as reference:

http://home.howstuffworks.com/home-improvement/plumbing/sewer2.htm

both the wastewater in and wastewater out pipes are on the same level, so a larger tank does not provide a larger reservoir to buffer water usage from the house. Therefore, the drain rate must rely on the characteristics of the drain field and have no relation to the tank size. Is this correct? So if my water usage increases, a larger tank will only provide more settling space and I will need to redo the drain field to accommodate the extra water?

I'd love to hear peoples experiences with, or understanding of, the details of septic systems.

Thanks!


----------



## Chris (Mar 19, 2015)

There will be no extra water or water flow from a larger tank, you are correct that there is only more room for sediment and thats it.


----------



## nealtw (Mar 19, 2015)

It will give the tank more time to to it's work and increase the life of the field.


----------



## JoeD (Mar 19, 2015)

It will give room for more solids before they digest. The solid "stuff" you flush does not liquify instantly. It takes time to digest into liquid.


----------



## bud16415 (Mar 19, 2015)

People did fine for many years with 200 - 300 gallon tanks. Most of the old systems bipast the septic tank with stuff like the laundry, kitchen sink and shower. My old system had a greese trap tank right before the leach field that took the soap scum out the gray water from the septic also came into that small grease tank. Other people ran wash water into a dry well. Now they want it all to go thru the septic tank. Another reason the bigger tanks are used is more people are being forced into sand mound systems and they require a pump and the pump has to dose the mound with X amount each cycle. they dont want trickle feed they need lots of flow to keep the injection points open. 

The majority of your cost wont be in the size of the tank so a 1000 isnt a big deal.


----------



## Ditchmonkey (Mar 20, 2015)

Thanks for the replies!

When I purchased the home last summer, the old 500 gallon tank had not been pumped in over 7 years and was doing fine. It seems that a lot of the hysteria surrounding septic tanks is completely unfounded. Unfortunately, the lid of the tank is rusting through so I'm going to have to replace it in the not-too-distant future. I'm hoping to be able to replace the tank and not the entire system.

Does anyone know how the flow rate for the drain field can be calculated? I'm trying to figure out if I add another bathroom and increase water usage whether the current system will continue to function adequately.


----------



## nealtw (Mar 20, 2015)

They do calculate need by the number of bedrooms, but if you are not adding people, there would be no difference.
I guess you could do a perk test in the field to see of the soil is still moving water and or break into the feild pipe to see how much restriction there is as failure to pump for extended periods could cause a problem with solids.


----------



## frodo (Mar 20, 2015)

care and use of septic tank


----------



## nealtw (Mar 20, 2015)

If it is only the lid, why not just replace the lid.


----------



## bud16415 (Mar 20, 2015)

Every state has different guidelines and I would suspect Oregon to be on the tougher end of the spectrum. Chances are you are allowed to have what you have because you are grandfathered in. once you start redesigning the system you will have to follow state and local guidelines and my guess is nothing you have will pass even though you are working perfect. 

I forget how many years ago I redid mine in Pa but the new unified code was taking effect in two weeks and I called my township and asked what I needed to repair my septic? They said in terms of paper work nothing but I better get the work done in two weeks or less as after that I would have to comply with what the perk test showed in my location and they knew that was going to be a very high sand mound system at least. I rented a back hoe the next day and had gravel dumped in my side yard and built the mound system I wanted and solved all my problems. Now when you drive down my road half the houses have huge mounds in the front yards that look like hell because they couldn&#8217;t get a perk test to pass in the back. 

If I was in your place I would figure out how to just replace the lid and not change anything until I had a problem. There is a lot you can do to keep your system healthy and going a long time.


----------



## Sparky617 (Mar 20, 2015)

Haven't had a septic tank since my childhood home got sewers when I was 10 or 11.  I believe you'll find in most area's Frodo's by-pass isn't legal. It is pretty commonly done, but not legal.

Getting the tank pumped out on a regular basis is the best bet for keeping it trouble free.  The solids will break down but there will always be sludge that doesn't break down.  If the sludge gets too deep you can damage your drainfield.  

If it is just your lid I'd do a new lid as others have mentioned.  A two foot by two foot precast concrete patio tile might be all you need to cover the hole and allow you to backfill.


----------



## JoeD (Mar 20, 2015)

Leach fields are often only rated to last a certain number of years. If you start messing with your current setup you get it condemned and need everything new. I would just try to replace the damaged lid if possible.


----------



## nealtw (Mar 20, 2015)

Out here we have this neat system where the installing company writes the report and it is filed like it was real. When a home buyer wants it checked before buying a house. The comppany comes in a fails the system and files it so now it gets condemmed. Good make work deal.


----------



## frodo (Mar 20, 2015)

check your codes,  black water grey water systems are legal

they are legal here.

what is not legal,  but done all the time..daylight the end of your leach field pipe..

your leach field will NEVER saturate


----------



## slownsteady (Mar 21, 2015)

When your field goes, you'll know it. Water will start to come to the surface and you might detect a smell when the wind is blowing right. Nj required me to have an engineer design my septic system. The previous one lasted about 19 years. The engineer said he could design it for the amount of bedrooms we were using, but he also knew the amount of bedrooms the house was listed for. The difference would bite me when we were ready to sell, as the the house couldn't be listed for more bedrooms than the field could handle. All that info is on record with the town.


----------



## Sparky617 (Mar 21, 2015)

Here is a listing, that could be out of date on the use of gray water by state.  I didn't read the whole thing, but several states allow a second tank and leach field for laundry water to separate out black water from gray.   But they do require a tank, which is in effect a septic tank to settle out solids from the waste water.  From the reading I've done on the subject you run the risk of clogging your leach field with link and clots of detergent (especially if you use powered detergent) if you run it directly into the leach field.

Gray water regulations are all over the place on what is allowed and what isn't.

http://greywater-systems.com/regs.htm


----------



## bud16415 (Mar 21, 2015)

If your state allows it or if you are doing it anyway you defiantly want a tank before the leach field for non septic gray water. 

What I did was run both my septic outflow and my kitchen and washing machine water into a common tank just before the discharge to my mound leach bed. I got my hands on a scrap locomotive air tank and burned off one end and planted it up and down with a couple holes for in and out lines. My tank is about 2&#8217; across and 6&#8217; deep. Inside that tank both in flows 4&#8221; have a elbow pointing down. The outflow has a Tee open at the top and with a 2&#8217; pipe going straight down. None of the outflow is glued together for cleaning if required. The idea being with soap and grease and such some will sink some will float and the outflow is taken from the middle of the tank. The leach field / mound is all gravity feed as I had enough drop. But is slightly higher than the surrounding ground. I have 12&#8221; gravel base and 4&#8221; drain pipe the type with holes on the bottom only, just covered with gravel. The pipes were made into a 16&#8217; square the gravel 24&#8217; square and the square frame has two cross paths. The idea is if any one path got plugged the water could flow around several other directions. My idea was to keep the pipes as high up as I could and they were covered with straw and then just a thin layer of top soil 4&#8221; and grass planted. Water can leach down or evaporate up and its worked well for over 20 years now with no smell.

When I have my tank pumped I also have them pump the grease trap and that is a waxy scum a couple feet on the bottom. 

I have always felt keeping all the bleach and soap out of the septic helped it work like it is supposed to. I pump mine every 2 years but could easily go 4 or more. 

I have photos of the whole thing and if can find them I will post a few. Like I said I could never build that system today with the new laws here. Maybe in some states you still could. 

On a side note we have one guy around here they call the midnight septic man. He shows up with a mini excavator and a 5 yard dump truck of gravel about 7:00 pm digs a hole dumps the load in runs a pipe over to your junction box covers it up and hauls away the dirt and is gone before dark in the summer. People do it because that&#8217;s all they can afford and it works for another 10 years or more. If you blink you miss him being there.


----------



## JoeD (Mar 21, 2015)

The thing is if you are going to run the grey water to the same leach field as the septic tank why not just run it through the tank. It is the same load on the field both ways. I don't get the point of bypassing the tank. It is always full anyway.


----------



## Sparky617 (Mar 21, 2015)

JoeD said:


> The thing is if you are going to run the grey water to the same leach field as the septic tank why not just run it through the tank. It is the same load on the field both ways. I don't get the point of bypassing the tank. It is always full anyway.



Joe,
I think the theory is to keep the bleach and detergent out of the tank.  The bleach isn't going to kill the beneficial bacteria digesting the waste unless you're running a commercial laundry service.  You're putting at most a couple of cups a week into a 500 gallon or larger tank with billions of bacteria happily munching away on the sludge.

So I'm with you, run it all through the tank and get it serviced on a regular basis.


----------



## frodo (Mar 22, 2015)

my illegal system,  was installed 10 years ago,  has never been pumped out,  

it has 2 toilets draining into the tank,  the tub,lav,washer,sink,  drain into a leach field.
my tank,  with only toilets draining into it,   is clean,  critters are fat wiggling and happy





it is the sludge from shaving,and washing hair,  that i want to keep out of the tank
the critters are a secondary concern

to me,  replacing 100' of 6'' perf pipe,  is cheaper than replacing a full tank
or, paying to pump it out every 3 or 4 years at $500 plus per wack
this is only my opinion,  works for me.


----------



## Ditchmonkey (Mar 24, 2015)

Thanks for all the info! I think a lid for a very old steel septic tank could be a very difficult item to find given that its the lids that always need replacing. Even if I did find one this won't be an easy item to ship. For now I have some old boards on the ground above it to ensure that the lid doesnt cave under a person.


----------



## frodo (Mar 24, 2015)

it does not have to be the correct lid,  grap some sheet metal,  or a garbage can lid [metal]
reinforce with some plywood.

personally,  i like my lid to be about 2''  below the grass,  i know where it is,  and its not a PITA to uncover.

it simple to do,,bricks and mortar,  make a square about 2'x2'    with a top.


----------



## slownsteady (Mar 24, 2015)

frodo said:


> .......it is the sludge from shaving,and washing hair,  that i want to keep out of the tank
> the critters are a secondary concern
> 
> to me,  replacing 100' of 6'' perf pipe,  is cheaper than replacing a full tank
> ...



If it's not going into the tank, where do you think it's going?


----------



## nealtw (Mar 24, 2015)

slownsteady said:


> If it's not going into the tank, where do you think it's going?



In the scetch he by-passed the tank.


----------



## frodo (Mar 25, 2015)

slownsteady said:


> If it's not going into the tank, where do you think it's going?



it's going into the leach field,


----------



## bud16415 (Mar 25, 2015)

A modern 1000 gallon tank most likely won&#8217;t be overwhelmed by the extra water from laundry and kitchen and the products that go down the drain with them. The system I talked about and built with a bypass was what I did having in place a perfectly good old time 300 gallon 3 stage tank system circa 1930 that are widely used still. The tank will never wear out but leach fields will plug up with time even in the best systems. I was up against replacing it all and going with a modern to code system and todays code around here barely allows for anything short of a massive mound system. In the 30&#8217;s thru the 60&#8217;s it was common for a house to be built on a half-acre or less lot with a simple septic system. Over 50 to 70 years these old leach fields have reached saturation point and people are left with hoping the towns extend lines out to them or are forced into a front yard mound that no matter how you try and hide it looks like a golf green with pipes sticking up or worse. 

So my repair at the time fell into the category of repairing a grandfathered system. That was a number of years ago and every community has different rules on what is considered a repair now.  

I wouldn&#8217;t suggest going straight with a bypass to the leach field unless like Frodo you have lots of room for new leach lines in the future when they plug with scum. I have had great luck with separating the soap scum out before the leach field with a smaller tank. It&#8217;s all about keeping all solids out of the field. Things like grease are liquid going down but turn solid when they cool down and mix with other products. You need to give them a do that.


----------



## Sparky617 (Mar 25, 2015)

I believe the daylight feature in Frodo's leach field is illegal.  I'm not a big government guy but on the home septic systems the regulations are there for a reason.  If you're on a well and septic you want the water that is going back into the ground or coming out on top of the ground from the daylight pipe to be as clean as possible.  The soil will take care of what gets past the tank, but a leach field running to daylight will put some nasty water out into the open.


----------



## bud16415 (Mar 25, 2015)

Daylight is illegal everyplace without a doubt. That&#8217;s not to say it isn&#8217;t done. 

We built a new home for my nephew about 15 years ago and all the modern code was in place at that time. His house sits on one end of 20 wooded acres he owns and he is surrounded by 100&#8217;s of acres of farm land and dairy farms. He is one guy living alone on rocky ground with a deep well at least 1000 feet from where he intended to put his septic leach field. We talked to his only neighbor across the street and down the road and asked what they recommended for septic and they said oh we have a 55 gal drum with a leach pipe about 100&#8217; long running back to the field and open ended, &#8220;has worked great for 20 years&#8221; was the comment. 
Keep in mind the farmer drives by at least once a day with a 20&#8217;000 gallon liquefied manure tanker and sprays a 100&#8217; swath up and down this close by farm land and his 20 acres are home to many critters and a lot of whitetail deer. 

We walk into the county office with a plan for a 1000 gallon tank system with a distribution box and 4 long leach lines set in gravel all capped on the ends and 1000 feet from any water source for a permit and got the old &#8220;Are you guys crazy do you think this is 1950?&#8221; You need to first do a percolation study and our person will come out and do the test. &#8220;OK what is required.&#8221; We ask. You need to pick your site and dig a hole 4&#8217;x4&#8217;x4&#8217; and out from that 30&#8217; in each direction 6 equal spaces you need holes 2&#8217;x2&#8217;x2&#8217; and then you need (7) 5 gallon buckets of water one for each hole or a tank or something to have that much water available. Then you have to make an appointment for him to stop out and it can&#8217;t be an exact time just a day and if he can&#8217;t make it he will call. Oh and hopefully it doesn&#8217;t rain while you are waiting. So we dig the holes make the appointment wait around a couple days and he shows up. He dumps the bucket in the center hole looks at his watch for 30 seconds and says it doesn&#8217;t pass and asks for a $50 check. Reason for failure it absorbed the water to fast. No need for the other 6 holes. What&#8217;s next we ask. Pick another location and request another test. We go thru this deal several more times always failing for the same reason too good of a perk. Every time a few days wasted and another 50 bucks. Finally we ask him as we are getting really far from the house if he would suggest a location that would pass and he tells us that&#8217;s not his job. But being a nice guy he would make a suggestion and he points to the highest point on the property higher than the house will be and the site of an old bank barn. And said that up on top of there might pass as the soil had been filled in maybe a 100 years ago. So we dig some holes and he comes out and dumps the water in and says yep it passes. So we say what kind of a leach field can we put up there and how do we get the water and materials to the top of this mini mountain. He says that&#8217;s not my job but bring your plans down and they will approve or reject them. And then he adds here is a card of a guy that designs systems and his rates start at $500. We rejected that offer and went on line and started our education on sand mound systems and in retrospect we should have wasted the 500 as it took months of back and forth to get a plan approved. We ended up with two 1000 gallon tanks and a lift pump. We had to build an earth ramp to even get dump trucks close to this spot 4 triaxle loads of various products to build the mound out of. He spent nearly as much on a DIY septic system as he did his house and wasted a good part of the nice weather we could have used building the house. All this for the maybe 5 gallons of real waste products a person would make in a month. 

I no longer wonder when I see someone buy a dumpy house that has water and septic grandfathered in and then do home renovations that mostly eliminates the original house.


----------



## Sparky617 (Mar 25, 2015)

Bud
One of the Appalachian Service Project mobile homes I worked on in WV last year had quite the daylight system for their sewage.  It was a straight pipe into a stream.  I'm still trying to get the smell out of my nose from the pile of poop at the end of the pipe. 

NEVER EVER go wading in a stream or lake in the mountains of WV unless you are high on a mountain.  :hide:


----------



## bud16415 (Mar 25, 2015)

Sparky617 said:


> Bud
> One of the Appalachian Service Project mobile homes I worked on in WV last year had quite the daylight system for their sewage.  It was a straight pipe into a stream.  I'm still trying to get the smell out of my nose from the pile of poop at the end of the pipe.
> 
> NEVER EVER go wading in a stream or lake in the mountains of WV unless you are high on a mountain.  :hide:


  Yep and the folks downstream take their drinking water out up stream and waste goes in downstream and on and on it goes. Thats what indoor plumbing did for us. Outhouses were really not a bad idea. 

  I saw a show on the water treatment plant for a city along the Mississippi River. The requirement on the water released back into the river was something like 100 times cleaner than the requirement for the processing of river water into drinking water. The guy asked the plant manager why are you discharging this super clean water down stream into the river instead of putting it back in with the drinking supply as it was so many times cleaner. His answer was no one wants to drink cleaned up sewage water no matter how clean it is. So they dump it into dirty water at quite an expense getting it so clean and the next city pulls it out and cleans it again and drinks it. 

  The same water has been here from the beginning of time it just goes around in circles.


----------



## Ditchmonkey (Mar 25, 2015)

Given the regulations and expense of a new system, I think I might go to a composting toilet and gray water system for my guest house.


----------



## nealtw (Mar 25, 2015)

more than you ever wanted to know.
[ame]https://www.youtube.com/watch?v=-Ih17XFOkSc[/ame]


----------



## Sparky617 (Mar 25, 2015)

There was no benefit of any cleaning on this water.  It was straight blackwater into the stream.  It is fairly common for people to run gray water out into their yards here.  This was the first time I ran into blackwater going into the stream.  They had small kids that would play there as well.  Ewww...


----------

