advice on tight tank idea

emery395

Well-known member
I'm look for advice as we are new to RV living.

We intend to live on same permanent site (our own 1 acre plot with water and electric) for 5 months per year during warm weather. Trying to decide the best method for handling waste. One idea is to bury a 1500 gallon septic tank and have it pumped out as needed.

Best way to vent tank?

With two people in RV and NO washing machine, any ideas about how often the tank might need pumping?

Things I have not thought of but need to??

Thanks in advance.
 

Lou_and_Bette

Well-known member
Emery, DW and I have been full timing for 6+ years and I will share some of MY experience. We usually need to dump our 45 gallon black tank every 7 or 8 days. This in itself is not a big amount but to, IMHO, throughly flush, I run 3-4 times that amount of clean water through the system each dump. We usually need to drain the 45 gallon number 1 grey tank, shower and bathroom sink, every 3-4 days, less in Cool weather and more in hot weather. We usually need to dump the 45 gallon number 2 grey tank when we dump the black tank. So, approximately 315 gallons per week. We winter on our daughters property and are on a separate septic tank system and have never had to have it pumped. I don’t believe there is a “vent” on this system but I may be wrong. In case you are thinking about just letting your grey water drain out without going into the septic tank, it is probably unlawful to do so and, more important, the grey water may actually stink more than the black water. I hope this information is helpful to you but your usage may vary.
 

emery395

Well-known member
thanks Lou_and_Bette that is very helpful.

Reason for not going with full septic system and leach field is cost of engineering work that is required to be legal. I may have to rethink that if pumping of tight tank would be required too often.

I would think the tank must need a vent because all house systems are vented back up through the roof vents or some other above ground venting in leach field.
 

MTPockets

Well-known member
I would guess an underground septic tank would require permits as well. Tank, installation costs I think would be a big chunk of permanent septic field cost.
 

travelin2

Pennsylvania Chapter Leaders-retired
Regardless of the options discussed here, in our neck of the woods the solution would be dictated by the local codes and the zoning officer, ie:tank plus leach bed/sand mound.


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danemayer

Well-known member
You should also investigate cost of pumping out the tank. If you have to do so every month, it could get expensive.
 

sengli

Well-known member
I know around here they charge per the size of the tank to be pumped. We get ours pumped once a year as a preventative thing, on regular septic.. and it costs $300 for a 1200 gallon tank. Thats sounds as if it could be expensive to just have a tank w/o a field.
 

GregP

Well-known member
Although we do not full-time with our RV, we have some experience with septic fields and related systems. If you are going to be permanently set up, I would recommend the installation of a permanent septic system. If you do not have the room, or suitable soil conditions to permit a drainage field with tile etc.; there are alternatives other than the holding tank you are thinking of. Also, some jurisdictions may not allow the use of holding tanks as they require regular maintenance which some people are loathe to do to save money. If you do install a septic system, it is not likely that the tank needs to be vented. Most venting in plumbing systems is actually designed to allow water to drain properly by allowing air in to "follow" the waste water down the drain instead of creating a vacuum. I am not a plumber though, so don't beat me up too badly on this.
 

emery395

Well-known member
I am going to take advice and install permanent septic system dedicated solely to the cyclone. I will create a short input pipe to the tank with a 90 degree bend and cap to dump into.

There a couple of issues that I would be interested in hearing about if anyone has relevant experience.

1. Would I be better off with 1 or 2 chamber 1500 g tank?

2. Is the sudden input of 20-30 gal of black tank followed by 10-20 grey tank discharge going to be too much for the septic tank to handle at once?

3. Any recommendations for a black tank additive that will not harm active septic bacteria?
 

Gaffer

Well-known member
Your county or state will probably decide which tank you must use. A local installer would know.
 

MikeR

Well-known member
I would also recommend that you let your RV black holding tank get pretty full before you dump it to your septic system. If you don't you could plug the black tank with solids.
 
I have mine on lot hooked to a traditional septic.
Been that way in this Heartland since I bought in January, and for 6 months in the small Coachman before this one.
I haven't had any issues at all. I leave both valves open all the time.
I have heard that if you send everything down the pipe too fast, depending on grade to tank and length, that the water will travel faster and leave debris
I am no #2 expert by no means!

One thing I do regret not doing is adding a cleanout in the pipe, so when friends come in RV's they could use that to dump.
I would say I will have to still do that
 

emery395

Well-known member
Thanks guys!

Hambone, I assume you meant to say "regret NOT doing". How is your system vented? Is it back through the RV because you leave the valves open?
 
Thanks guys!

Hambone, I assume you meant to say "regret NOT doing". How is your system vented? Is it back through the RV because you leave the valves open?

Yes, you are correct, I fixed it, the post that is...

It is a regular septic, like at my house, actually there was a house here, so I just used it, works great.
I don't think it vents anywhere. I have not smelled any sewer gas in the camper.
I always send extra bowl of water down afterwards though..
There are a couple reasons I leave valves open. First one was I was here when it was cold and they were froze in the closed position. That could of been bad.
2nd with the big slides of this unit and the slope of the hill, they are not easy to get to
 

danemayer

Well-known member
I have mine on lot hooked to a traditional septic.
Been that way in this Heartland since I bought in January, and for 6 months in the small Coachman before this one.
I haven't had any issues at all. I leave both valves open all the time.

Generally if you leave the black tank valve open all the time, the liquids will go down the sewer but some of the solids will stay behind. Over time this leads to a buildup of hardened solids in the tank. As some people have found, eventually the black tank no longer drains.

How long? It may depend on how you use the facilities as well as the slope of your plumbing components. But it's hard to imagine that everything you put in the tank is flowing into the sewer if you leave the black tank gate valve open all the time.
 

wdk450

Well-known member
I have mine on lot hooked to a traditional septic.
Been that way in this Heartland since I bought in January, and for 6 months in the small Coachman before this one.
I haven't had any issues at all. I leave both valves open all the time.
I have heard that if you send everything down the pipe too fast, depending on grade to tank and length, that the water will travel faster and leave debris
I am no #2 expert by no means!

One thing I do regret not doing is adding a cleanout in the pipe, so when friends come in RV's they could use that to dump.
I would say I will have to still do that

Regarding your leaving valves open and not doing a regular dump when the tanks are full. Someone already mentioned the building up of a "tower of poop" in the black tank under your toilet when you leave the tank valves constantly open. What you normally get with a closed black tank is NOT solids and liquid, but a brown "soup" as the solids are soaked in water for a long period before dumping. Add to that the effect of the fresh water tank washer. Toilet paper is also supposed to disintegrate upon soaking in water. If you have one of the clear sewer elbows at the discharge pipe (like I do), you can SEE the soup with very little solids. If you then subsequently dump the kitchen tank composed of dishwater with high concentrations of detergent, then finally the bathroom sink/shower tank composed of mainly clear water, you have washed out and rinsed out the sewer hose leading to your septic connection. Added to that, the high initial flow rate when you first open up the black tank helps move out any solids present better than the very low flow after a #2 flush with the valve constantly open.
 
Generally if you leave the black tank valve open all the time, the liquids will go down the sewer but some of the solids will stay behind. Over time this leads to a buildup of hardened solids in the tank. As some people have found, eventually the black tank no longer drains.

How long? It may depend on how you use the facilities as well as the slope of your plumbing components. But it's hard to imagine that everything you put in the tank is flowing into the sewer if you leave the black tank gate valve open all the time.

One thing I do that I failed to mention, I hook up the water hose to the black tank cleanout occasionally and let run for a bit

- - - Updated - - -

Regarding your leaving valves open and not doing a regular dump when the tanks are full. Someone already mentioned the building up of a "tower of poop" in the black tank under your toilet when you leave the tank valves constantly open. What you normally get with a closed black tank is NOT solids and liquid, but a brown "soup" as the solids are soaked in water for a long period before dumping. Add to that the effect of the fresh water tank washer. Toilet paper is also supposed to disintegrate upon soaking in water. If you have one of the clear sewer elbows at the discharge pipe (like I do), you can SEE the soup with very little solids. If you then subsequently dump the kitchen tank composed of dishwater with high concentrations of detergent, then finally the bathroom sink/shower tank composed of mainly clear water, you have washed out and rinsed out the sewer hose leading to your septic connection. Added to that, the high initial flow rate when you first open up the black tank helps move out any solids present better than the very low flow after a #2 flush with the valve constantly open.

Well said Bill, especially the "Tower of Poop"!!
Reckon I will try that during the warm months.
 
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