Septic Tanks + Saltwater, help me prove a point

ichthyogeek

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I've been doing water changes on a 55 gallon tank for my parents for the past couple of years. It's ranged anywhere from 10 gallons to 25 gallons per change and at a rate of every day/other day to months of no changes due to me being in college at the time. The pandemic is making things not okay, but I'm trying my best to hang in there and stay sane. Part of this has been me setting up some (now failed) brine shrimp cultures outside (failed due to lack of maintenance), which are about half salt half freshwater. Anyways, I was going to dump them out today like I've done for the past 8 or so years without problem, and a person we shall not address decided to tell me that pouring the half salt half freshwater down the drain would ruin the septic tank. Note: there are currently four people in the house I am in, who all use water rather copiously (showers, garden watering, water changes, RODI unit, laundry, etc.). Now, most esteemed members of the forum, somebody please tell me that I'm not crazy, and that tossing highly diluted water down the drain for the Nth time in a row is not going to ruin the septic tank?
 

VAFish

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It will not harm your septic tank as long as your septic tank is pumped regularly. If the concentration of the salt gets too high, it can have adverse effect on your leach field. The salts will bind with the minerals in the soil and will clog the soil pores.
 

mfinn

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Dumping even a hundred gallons into a septic tank will not hurt it.
I've been dumping up to 100 gallons every 2 weeks into my septic tank for 30 years and it's still working.
Last time I had it pumped ( 3 years ago ) I brought this subject up to the guy doing the work as I've always done.
He said he would check it out as best as he could and let me know if he saw any damage.
There never has been.
Any for what it's worth, the drain field is fine too. Grass grows ( when I water it)
 

TriggerFinger

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Septic home owner here. I’ve been advised that the salt build up *could* cause issues in the long run and that’s it’s not recommended on a system as old as mine; approaching 24 years old. I spent $5,000 just 9 weeks ago to have new laterals dug and installed as mine were clogged. I dump my saltwater in the rain gutter/drainage ditch out in front of the house. The grass is dead but the deer absolutely love that ditch now.
 

LiveWire

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IMO Dumping saltwater in your septic will not harm it at all. Think about it, many homeowners have water softeners and in order to regenerate the resin that attracts the ions (generally calcium and magnesium) that make the water hard the resin needs to be rinsed with a high gravity salt brine which dumps directly into the septic.

So if salt caused septic issues then anyone using a water softener would be having septic issues right?
I have yet to hear that having a water softeners causes septic issues so I would believe that dumping aquarium saltwater into the septic would not cause any issues either.
 

ShepherdReefer

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This is what I am going to do. We are in the plans of adding to the home that will include a 500+ gallon tank with a filtration room. I am going to add a drain that will just drain under the ground instead of the septic/lateral lines.
 

TriggerFinger

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This is what I am going to do. We are in the plans of adding to the home that will include a 500+ gallon tank with a filtration room. I am going to add a drain that will just drain under the ground instead of the septic/lateral lines.
I’ve though about digging my own leach field away from my ancient septic system. I don’t have NEAR that big of a tank so won’t have as much water but I think that’s a good idea! Will you be posting the process on your build thread? Would love to see what you come up with and how it works out.
 

ShepherdReefer

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I’ve though about digging my own leach field away from my ancient septic system. I don’t have NEAR that big of a tank so won’t have as much water but I think that’s a good idea! Will you be posting the process on your build thread? Would love to see what you come up with and how it works out.

I will be adding this to the thread, we are still in the planning stage waiting on the estimates to get back. One good thing going for us, we live on 1.34 or so acres.
 

Tokash23

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Just a thought from someone who has experience with pumping septic tanks, while some or most of you may not have immediate issues just the fact that there is a remote possibility of an issue would stop me from doing it. Salt is highly corrosive and can cause damage to not only the tank but plumbing running to the tank (older homes may use cast iron or terracotta piping which is no good in its own) and as some have said the leech field. A whole new system (in the event of failure) can cost 15k or more depending on a lot of things. Just my 2 cents do what works for you though.
 

mtfish

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This is what I am going to do. We are in the plans of adding to the home that will include a 500+ gallon tank with a filtration room. I am going to add a drain that will just drain under the ground instead of the septic/lateral lines.
That is exactly what I did when we built our house. It is not the salt water in the drain field. Saltwater over time can attack the cement of the septic tank. Now, how long would it take to do harm? Maybe we don't live that long, but I will never find out in my case. I had them dig a 4ft x 4ft hole, added perforated pipe and backfilled with pea gravel. Drain from my fish room goes into the pea gravel hole.
 

ichthyoid

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The ancient Romans used to salt the fields of adversary’s, which had given them an especially tough fight. The salt destroyed the soil’s fertility for generations, and also their enemy’s ability to survive in that region along with it.

I have a septic tank & after a lot of research & thought, decided not to dump used seawater into my septic system, for three reasons-

-potentially upsetting the ionic balance of a system designed to bacterially process our home’s waste & maybe cost me a lot of $$$ isn’t in my best interest.

-salt (sodium specifically) destroys the soil’s structure & aggregation ability by displacing other, especially multi-valent, cations (potentially for generations, see above).

-salt/sodium is known to damage cement, weakening it’s structure. Most septic tanks (including mine) are made out of cement.

This won’t be a popular reply & based on past discussion on this topic in other forums, there will likely be a lot of debate & disagreement. That’s all fine, but they don’t pay the bills at my house either. Why take a chance? My $0.02
 

NanJ

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That is exactly what I did when we built our house. It is not the salt water in the drain field. Saltwater over time can attack the cement of the septic tank. Now, how long would it take to do harm? Maybe we don't live that long, but I will never find out in my case. I had them dig a 4ft x 4ft hole, added perforated pipe and backfilled with pea gravel. Drain from my fish room goes into the pea gravel hole.
This is similar to what we did for our 300g system. A separate drain in the basement aquarium maintenance room for salt water. The drain goes out about 50 feet from the house and drains into a rock bed in a field. Out RODI waste water also drains to this pipe. No grass/weeds have died in 20 months of use.

I did extensive research about saltwater in a septic system and never found any conclusive information. Some soil types will bind the salt and result in clogging of the leach field but I don’t remember the details of the types. That is the only solid piece of information I found. It was easier to add the dedicated drain than to pay for a soil scientist to help us with a decision. Our local Environmental department that regulates septic systems had no experience with this situation.
 

VAFish

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I will post again. I am in the business. I am a licensed soil scientist. This is part of my job. Here are the things you need to consider before dumping anything into your septic tank.

1. Do you a septic tank to drain field or whether you have an addition pretreatment unit prior to your drain field.

In a septic tank to drain field, generally your septic tank is sized to allow the natural dissolution of suspended solids in the effluent. Therefore, therefore there should be sufficient effluent in the septic tank to dilute the concentration of the salt. Remember over time, this concentration will increase as you add more water from your tank. This is due to the fact that septic tanks utilize a sanitary tee to allow effluent exit the tank and this tee is only 18-24 inches long to penatrate into the clear zone of the tank. This means there is always effluent in your tank and therefore the concentration can increase. If the concentration of salt is high enough it will kill both the aerobic and anaerobic bacteria in your septic tank which is essential to the treatment of effluent.

If you have a secondary treatment unit (ATU,packed bed filter, etc.) the concentration of salt becomes even more critical. These units utilize either forced air or passive air to increase the concentration of aerobic bacteria to increase the treatment of effluent. The design and sizing of these treatment units is based on residential wastewater strength. There the introduction of salt into the effluent can have disastrous consequences on the functionality of the treatment unit, if the salt concentration is too high.
With respect to the effects of high concentration of salts in the effluent once it enters the drainfield and interests with the minerals in the soil. Virginia Tech has conducted studies and has found if the concentration if sufficiently high 2 things occur. One, the salt reprecipitates and will clog the soil effluent interface. Secondly, the salts will bind with certain minerals in the soil and change the chemistry of the soil. This change in soil chemistry has shown to have severe consequences to the functionality of the drainfield.

Those are the bad. If proper maintenance of your drainfield and septic tank are done the issues should be negotiable. These means routine pumping and possible more frequent pumping of your septic tank.

If you have an additional treatment unit, I would recommend testing the salt concentration passing through the unit and notifying your maintenance provider of what your are doing to monitor the effects.
 

mtfish

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Hey @VAFish . What is your take on saltwater affect on cement tanks? That was my main concern when installing the septic tank and the reason I went the direction I went.
 

KStatefan

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The ancient Romans used to salt the fields of adversary’s, which had given them an especially tough fight. The salt destroyed the soil’s fertility for generations, and also their enemy’s ability to survive in that region along with it.

I have a septic tank & after a lot of research & thought, decided not to dump used seawater into my septic system, for three reasons-

-potentially upsetting the ionic balance of a system designed to bacterially process our home’s waste & maybe cost me a lot of $$$ isn’t in my best interest.

-salt (sodium specifically) destroys the soil’s structure & aggregation ability by displacing other, especially multi-valent, cations (potentially for generations, see above).

-salt/sodium is known to damage cement, weakening it’s structure. Most septic tanks (including mine) are made out of cement.

This won’t be a popular reply & based on past discussion on this topic in other forums, there will likely be a lot of debate & disagreement. That’s all fine, but they don’t pay the bills at my house either. Why take a chance? My $0.02


How do you dispose of your saltwater then?
 

h2so4hurts

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If all of the detergent from my washing machine doesn't destroy my septic tank I highly doubt 60 gallons a week from my water changes is going to do anything to it (and it hasn't in the 5 years I've been doing this). I agree that if you get a massive concentration of that salt in your tank you could potentially kill the bacteria, but why would that happen? What would concentrate the salt in there vs it just draining as a dilute solution into the drain/leach field?

I wish the saltwater killed everything in my drain field. I currently have to spray round up on it twice a year to keep the shrubs/trees/weeds from taking over.
 

ichthyoid

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I store old water & pour it out when it’s raining. Here in Georgia, that dilutes it beyond concern.

I’m currently looking into rain sensors, like what is used on sprinkler systems. My goal is to run a pvc pipe from my garage down the side of the driveway. Then tie the sensor into the Apex, which will automatically pump out the storage container when it rains.

If that doesn’t work out to be feasible, I’ll still run the pvc, and pump out to the street with a freshwater flush afterward. Either way, I’m automating all of the water handling. I’ve been in this hobby for decades. Water changes are the equivalent of mowing grass, which I’m about over too! Now, if we only had a robotic glass cleaner?

I use a Masterflex to automate continuous water changes from a mixing station.
 
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I store old water & pour it out when it’s raining. Here in Georgia, that dilutes it beyond concern.

I’m currently looking into rain sensors, like what is used on sprinkler systems. My goal is to run a pvc pipe from my garage down the side of the driveway. Then tie the sensor into the Apex, which will automatically pump out the storage container when it rains.

If that doesn’t work out to be feasible, I’ll still run the pvc, and pump out to the street with a freshwater flush afterward. Either way, I’m automating all of the water handling. I’ve been in this hobby for decades. Water changes are the equivalent of mowing grass, which I’m about over too! Now, if we only had a robotic glass cleaner?

I use a Masterflex to automate continuous water changes from a mixing station.
I can tell your not in an ATL HOA subdivision- because I get flank from my HOA if I let car wash (soap free) water run into the gutter. All my water change water goes into the regular sewer, but it’s only like 30 gallons every two weeks.

thsts going to change soon though- we just decided to move to a lake Lanier frontage that’s on septic, and the field is 30 feet away from US Corp’s engineers/public use land.
 

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