Low-flow toilets vs septic systems

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Mikey

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I was talking to a septic system designer the other day in connection with a questionable septic drainfield on a home I bought. I mentioned that I was planning to replace all the old 3-gallon toilets with modern low-flow or dual flush units (specifically, Drake or Aquia).

He suggested I think about that some more, arguing that there are two failure modes for septic systems: hydraulic failure, where the drainfield cannot absorb/perc the incoming fluid effluent, and biologic failure, which can be accelerated by an effluent with a high solids content. Low-flow toilets result in a more solids-rich effluent, and could thus aggravate a borderline situation.

I'm just starting to do the research, but it seems to be a reasonable argument, somewhat dependent on the ratio of flushes to showers and other "grey water" waste. Our 2-person household currently averages about 100gpd, using 1.6gpf Drakes. Estimating 10 flushes per day, that means about 16% black-water, 84% grey or better. The ratio would change to 26/74 if we had 3-gallon toilets installed. I have no idea what an ideal ratio might be; at what point do you start worrying about biologic vs hydraulic failure?
 

Gary Swart

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Just where do you think you will get the 3 gpf toilets? I think you've been fed a line BS.
 

Smooky

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A two person home such as yours is producing the same amount of solids as any other two person house. If you have a modern tank it should have a baffle wall and an outlet tee or an effluent filter. If you have low flow fixtures , you are getting better settling of the waste in the tank. Also there is less effluent going into the drainfield, so you are less likely to flood it out. The minimum size septic tank in Florida is 900 gallons. The tank stays full of liquid up to the bottom of the outlet. It is important to have it pumped out every 5 years or so. More often if you have a food waste disposer.

If the tank fills with solids, sludge, grease, oils etc, it will began to pass through the baffel wall. If the tank is under sized for the amount of flow the solids will not have a chance to settle and can pass through the tank. When that happens, a bio-mat forms on the bottom of the trench. Over time this bio-mat can clog up the soil and cause a failure. That is why pumping it out is important. This does happen but most failures are probably due to too much flow and are flooded out. That can occure when the actual flow is greater than the design flow.

All septic systems have limits to what they can handle as far as flow. Also you need to be smart about not pouring grease down the drain. I don't have nor do I recomend installing a food waste disposer if you are on a septic system.
http://www.floridahealth.gov/statistics-and-data/eh-tracking-and-reporting/_documents/64-e6.pdf#search=
 
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Mikey

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Just where do you think you will get the 3 gpf toilets? I think you've been fed a line BS.
You misunderstood; the new house has 3gpf toilets; I'm thinking of replacing them. So if anyone wants some 3gpf toilets, let the bidding begin :).
 

wjcandee

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Low-flow toilets result in a more solids-rich effluent, and could thus aggravate a borderline situation.

This guy is a septic system engineer? Did he get his degree from a box of Cracker Jack? What he said is just dumb as dirt.

The effluent that goes into the drain fields has the solids removed (reduced) in it by virtue of the waste settling in the septic tank. Scum layer on top, sludge layer on bottom, clear water in the middle. The clear water is what flows into the drain field.

Less fluid coming from the house to the septic tank means a longer time for the bacteria to work on the effluent and a longer time for the stuff to settle. The settling in the still-ish water is what removes the solids from the effluent. Adding a couple of gallons of water per flush to the septic tank does nothing but (to a small degree) reduce the period of time that the clear water stays in the settling side of the tank. So it would result in, to a small degree, a denser effluent.

He also seems to assume that there's some mechanism between the toilet and the tank that somehow dissolves everything solid into the amount of water that is used to flush. That's not how your DWV system works, of course. The flush water transports the waste to the septic tank, and usually not all in one flush. There's a whole thing about "drain line carry", and the reality is that some stuff will go all/most of the way, and some of it won't. Taking a shower, running the washer, running the dishwasher, a subsequent flush, etc., all move the solid material along the line and ultimately into the septic tank, where the bacterial action and settling action all occur. If your septic tank is properly-sized, the 1.6gpf toilets are unlikely to make any material difference in your septic system's operation, now or 10 years from now. If it's a bit small, they will help, to some degree, increase the settling time, which becomes more important if it's a bit too small. If it's larger than needed, well, then they will, to a teeny degree, help make the water even cleaner.

Anyway, replace with confidence!!

[Just read Smooky's post. He covered some of this already, and he is correct. He is also correct that regular pumping is important. A good, honest, septic system guy can measure the various layers and give you an idea of how often you need to pump based on your particular usage and habits.]
 
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Mikey

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All very interesting; thanks. This system was designed by a licensed septic system designer (not the same one I was talking to), but the installer (a possibly licensed backhoe operator) apparently ignored the design and built it his way. The only as-built drawing available is a sketch made by (I assume) an inspector in 1992, which looks nothing like the accepted design, but was approved anyway. (A lot has changed since 1992). There is one 1125-gallon, 2-compartment septic tank (52" deep), followed by a 250-gallon pump tank. There is no effluent filter, but I will probably be adding one.

While effluent is wastewater treated to some degree, it is not water; a lot of research has been done to quantify this and develop standards for maximum levels of the three major factors -- biochemical oxygen demand (BOD), total suspended solids (TSS), and fats, oils, and grease (FOG) -- which typically determine septic tank effluent strength. Research studies and field experience have shown that, as BOD, TSS, and FOG loading rates increase, the probability of biological clogging and hydraulic failure increase. (See: http://www.doh.wa.gov/portals/1/Documents/Pubs/337-105.pdf for a summary.)

County records show my tank was pumped in 2003, 2008, and 2016, with scum/sludge reported as 24"/6" (one compartment, no pump tank reported), (14"/8", 3"/5") (two compartments, no pump tank) and (1"/11", 0"/0", 0"/0") (compartment 1, compartment 2, pump tank) respectively. I guess it's encouraging to see more accurate data and better numbers as time goes on.

In 2008, the county said, "A septic tank should be inspected every three years and pumped only when needed. If the combined sludge and solids exceed 1/3 the total volume of the first compartment and/or 1/3 of the total volume of a single compartment tank, or if the sludge layer is less than 12 inches from the bottom of the outlet tee and the floating mat is less than three inches from the bottom of the outlet tee or 1 inch from the top of the outlet tee, then the tank should be pumped. Pump tanks should be pumped when any measurable amount of sludge or scum is present."

The only guideline I find today is in a Health Department pamphlet, saying "septic tanks need to be inspected at least every 3 years and pumped as needed to prevent solids from damaging the drainfield."

I'm going to buy the new toilets.
 

Terry

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Some people use something like Bio-Clean in their septic systems. It helps to break down the solids and the grease.

A blend of bacteria and enzymes. The bacteria are natural, not genetically-engineered.
 

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CountryBumkin

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County records show my tank was pumped in 2003, 2008, and 2016, with scum/sludge reported as 24"/6" (one compartment, no pump tank reported), (14"/8", 3"/5") (two compartments, no pump tank) and (1"/11", 0"/0", 0"/0") (compartment 1, compartment 2, pump tank) respectively. I guess it's encouraging to see more accurate data and better numbers as time goes on.

In 2008, the county said, "A septic tank should be inspected every three years and pumped only when needed. If the combined sludge and solids exceed 1/3 the total volume of the first compartment and/or 1/3 of the total volume of a single compartment tank, or if the sludge layer is less than 12 inches from the bottom of the outlet tee and the floating mat is less than three inches from the bottom of the outlet tee or 1 inch from the top of the outlet tee, then the tank should be pumped. Pump tanks should be pumped when any measurable amount of sludge or scum is present."

The only guideline I find today is in a Health Department pamphlet, saying "septic tanks need to be inspected at least every 3 years and pumped as needed to prevent solids from damaging the drainfield."

I'm going to buy the new toilets.

I'm in central FL too. I didn't know the county kept records on the when the tank was pumped. I'm curious about mine, are these records available on-line somewhere (or does it require a trip to the Seminole County records office)?
I just had mine done but I didn't get any info regarding the levels in the tank.
 

Terry

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Drain Field – Mix 1lb of BC with 2 gallons of water for every 50 feet of drain field line. Apply directly to drain field through distribution box, vent pipes or clean out. Repeat the above dosage at 3 week intervals until 3 – 6 cans have been used.

It sounds cheaper than digging up what you have.
Plumbers have been selling the stuff for years.
 

Mikey

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I'm in central FL too.
Well, I'm in central FL right now, but not for long. I'm moving to Washington (state) shortly, and the septic tank, field, etc., I was describing are in Kitsap County, where (these days) meticulous records seem to be kept wrt septic system design, installation, and maintenance. Whenever property is transferred, the septic system is inspected by the health department, and in general they seem to be very conscientious.

Florida's oversight of "onsite sewage treatment and disposal systems (OSTDS), commonly referred to as septic systems" starts at the state level (see: http://www.floridahealth.gov/environmental-health/onsite-sewage/index.html), but permitting and inspection of OSTDS is handled by the Environmental Health Section of the Florida Department of Health in each county. For you, that's in Sanford (407-665-3000). I looked at their website, but they seem to be mostly concerned with Zika these days. They do maintain a web page at http://seminole.floridahealth.gov/p...ntal-health/onsite-sewage-disposal/index.html, which has a nice list of Dos and Don'ts, but not much concrete guidance.

There's a site (http://www.septicsearch.com/) that lets you search state-by-state for septic system data. Going to Seminole County gets you to http://www.septicsearch.com/Pump/Default.aspx?stype=1&cidd=636060932897616369, where you can enter your property address and search for records.

Finally, if you Google "Florida Statutes Septic" there's a ton of stuff that may be helpful, but I ran out of time to follow those breadcrumbs much further :). The Florida Statute governing OSTDS is at https://www.flsenate.gov/Laws/Statutes/2016/381.0065.
 

Gary Swart

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I've been lurking on this forum for several years, and it seems that codes and code enforcement varies widely from state to state and in many cases, from county to county within a state. What is not only legal in one state is illegal in others, codes that are strictly enforced in one state are ignored in others. In some states, you are not allowed to touch the plumbing, in others, they could care less what you do. It's crazy!
 

flapper

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Terry

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So it cleans the pipes but what about the tank; doesn't the septic tank always have plenty of bacteria? And the doodoos add bacteria.

I learned a bit about bacteria and what lives in your stomach after going through colon cancer, and then going to India.
India taught me that what was in your stomach mattered. Going through radiation, chemo, several colonoscopies and three surgeries, there wasn't much left inside. Being in India was a big help. That two week trip lasted me for six months back home. When the effect wore off, I went to probiotics. That has been keeping things working well for me.

There are many things that can harm septic tanks that wind up being flushed down the drains.
If the septic system above had the correct bacteria in it, would it be having any issues?
I have been using and selling products made for septics for a long time.

india_1574.jpg


Varanisi, India on the Ganges River
We were far out in a boat. Some late comers would walk from boat to boat to get out to where their friends were.
Walking through the crowds to get to the river was very interesting. In India I learn that walking is done at a steady slow speed as you wind your way through crowds. Change your speed and you start bumping into people.

india_1795.jpg


The next morning.

india_4235.jpg
 
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Mikey

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Yes, what's in (or not in) your gut matters a lot. Nowadays, for those in the not-in situation, they're doing poop transplants (
).

Beautiful pictures; obviously not made by MY cellphone. I have a good friend from India, who keeps threatening to give us a guided tour of his country, but so far, we've resisted. It is a very beautiful and culturally rich country, but fraught with some modern problems that have discouraged me from traveling there (and to lots of other places as well).

I was lucky in the cancer lottery - I had prostate cancer, and was successfully treated for it with proton beam therapy 6 years ago. No mess, no pain, few side effects. The real hope for the future, imho, is immune system therapy; the current research results are stunning, and suggest that all cancers might be curable using the same tools.
 

Terry

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You would love India. My brother from Washington DC goes there a lot. They played this in theatres in India and other parts of the world.
My brother is wearing the green shirt in this trailer for the movie. On one of his trips he was able to secure bids for reducing the cost of drug treatments to be used in Africa.


https://en.wikipedia.org/wiki/James_Love_(NGO_director)

I found India to be an exciting place to explore. It is so different than here in the US, it's eye candy 24/7.
I recommend it.
 
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