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Septic tank - problem?

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(@genki)
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Our property is not connected to municipal sewage, but includes a septic tank "soakaway" as described by the previous owner. The septic tank has two inspection panels (manhole covers) in patio above it but that lead to the top of the septic tank (one would assume), but take the manhole covers off and it’s just concrete underneath, no access unless you smash into it... Everything I’ve read on septic tanks talks about either emptying them or at least inspection hatches to check health and function of tank but I don’t seem to be able to do either. I’ve Googled the hell out of this but can’t seem to find anything. I guess my next step is to call in a plumber and get some advice, but thought I would check with this knowledgable community first as hope someone can share their knowledge and experience.

 

pictures attached 

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(@thomasribatejo)
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Something's definitely off here!

I would speculate that the septic tank pre-dated the widening of the concrete - but cannot work out why, other than sloppy work, they would have concreted over and then put manhole covers that serve no purpose (other than perhaps to fool people into thinking the job was done right!)

[If I understand correctly, you open either manhole cover, and just see the same concrete immediately beneath it?]

Certainly, pretty much regardless of the type of tank, you need to be able to inspect it.  Soakaway types are not uncommon here, and are not as bad as they sound - and if they're working well, they shouldn't need emptying under normal use (= provided you're not putting loads more waste down the system than was envisaged when the tank was specified - and by the way, you'd need to minimise chemical-based products, bleach, etc, ideally using products labelled as septic tank suitable).

I suspect a plumber is unlikely to want to get into this (though some may).  Typically (but location-dependent) your municipal water supplier may be able to send someone, or recommend someone; or there will be one or more private septic tank companies (emptying, installation, etc) serving your area.  I'd speak to them.  

This may just be a question of access for inspection - the tank may be perfectly functional and adequate, if only you could get into it!

If it needs substituting, consider its location.  It's hard to be sure from the photos, but aside from being under a patio, it's relatively close to the house, and may be higher than and close to other features (pool, outdoor leisure space, cultivation).  Replacement, if required, should take into account current regulations; and all such water systems should technically be registered with the APA (Portuguese environment agency) though few legacy systems, and many new ones, aren't.

 

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(@aspidistra)
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@thomasribatejo I don’t understand the soakaway thing. That is what I am supposed to have. When I look into the manholes, I just see a big concrete (I think?) tank.

How does the soak away bit work? Is it that the tank has some holes in the bottom of it and stuff drains away there or something? I would have thought there must be a place where the pLang’s grow greener because of it but I don’t see anything.

Genki, sorry about your problem, that does sound like someone did a botch on it, doesn’t it? 

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@aspidistra Honestly, the kind you're describing, I can't rightly say.  Is it possible you were misinformed; or that there is a second chamber which has some means of outflow?

A "traditional" soakaway tank here (if there is such a thing - for this reason, I avoid saying "standard") has some relatively obvious small outflows.  Ours is tijolo, of the kind with holes through the length, and at intervals, one is placed endways on.  I have not, for obvious reasons, gone to the bottom to see if the same is true there!  (I wouldn't expect it to go out the bottom, else it might drain too rapidly - but I am [thankfully] not an in-depth expert in septic tanks!)

We cannot discern any impact, positive or negative, on the surrounding land or growth, in our case - only a lack of growth around the immediate area, due to lack of soil depth.

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(@aspidistra)
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@thomasribatejo oh that’s interesting. I don’t think the previous owner really knew what she had, only that she had never needed to empty it. I think I need to get a septic tank company to just look at it for me.

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(@jonesdn2020)
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@aspidistra Many of us grew up with septic tanks since sewer systems were only in larger cities. The key to them is the soil. We recently had an issue with a family members existing septic tank. The soil failed the percolate test and the property was now uninhabitable.

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@thomasribatejo Thanks for the APA information. I am trying to decipher Portugal building code and the nuances with the Eurocodes. My first concern is when and if the plumbing code changed to require the venting of the plumbing?

Many of us in Lisbon, with older apartments, have the common sewage smell issue so I am trying to identify what year of a build to rent that does not have that problem.

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@jonesdn2020 We're not particular experts in new installations of waste systems (and the next week doesn't allow for time to research), but it seems the most relevant applicable legislation may be 

Decreto Regulamentar n.º 23/95 de 23 de Agosto

It does not appear to have been superceded, from a rapid check. 

Bear in mind that, in practice, monitoring of these things being done properly is inconsistent, so build date is less of a guarantee of compliance than it ought to be... and older buildings, if refurbished, may have been decently retrofitted...

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(@genki)
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@thomasribatejo Thank you as always for your helpful and knowledgable response to my post. Its good to know that Im not way off base with my thoughts and equally the direction of research is with the Municipal Water or specialist rather than plumber (I wouldn't have realised that). I think you are correct on the concrete 'patio' development and how it is likely that they have simply concreted over the top as they've extended the area, but still for the life of me cannot work out the logic of keeping faux inspection hatches. I dont have a picture handy but what is even more baffling is that one you remove the inspection hatches the gap to the concrete below is just a couple of inches and concreted into the centre are rebar style handles... but much as I scratched away at the edges and surface is clear that they serve no purpose and are not handles at all.... its all very odd. The cement at the top (under the hatches) is as new as the new patio area and so part of that same work. 

Apart from just wanting to know the health of the tank, the ground floor shower and basin flow is really slow and so need to investigate why which leads me to the issue. I suspect that I will end up getting someone to dig it up and install a new one further down the land (see picture) in the soil rather than under the patio. But that's a scary cost I would imagine so trying not to knee jerk to that outcome.

 

 

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(@thomasribatejo)
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Posted by: @genki

concreted into the centre are rebar style handles

Were it not for the other bits you mention, this would make some sense - concrete tanks sometimes have concrete hatches with such handles, which is a pain, as they get stuck shut, are hard to grab and manoeuvre, etc...  We have a water storage tank with such a lid, and grit and growth having got in around the edge, it's stuck fast.  It is just possible yours did work and make sense when initially done - or it could be a flaw in someone's logic...  I feel for you, and wish I could provide a convincing explanation!

On the slow flow, we have the identical problem in an 80s ground floor bathroom (and it's unrelated to the septic tank in our case).  You may have done this already, but try a plumber's snake (get a good long but thin one - they're inexpensive) and also try a decent drain cleaner (Destop in a purple bottle, which says it has two doses, is the best I've found that is compatible with septic tanks - half the bottle, leave it an hour or two, then rinse with cold water).  It's quite possible this issue is inadequate drop on the pipe run, pipe joints being done incorrectly causing sticking points, and/or massive build-up.  Another thing - not to be combined, for risk of the Destop coming back up! - is to fill everything else, plugs in, and then release all at once.  It'll burp back, most likely, due to the air lock, but can help...

Back to the tank... it may well be best to try to bypass your old one, to a new tank - there are good ones available, and if it's installed properly and for you, it may take away the headaches.  Just not something one wants to have worry about, I know!

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(@genki)
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@thomasribatejo thank you as always. We have tried a drain cleaner but not the brand or intensity you suggest mainly through not understanding the septic system. I did plunge the downstairs shower outlet and it brought up what I can only describe as a black ash like substance (fine black particles). But again with my lack of knowledge on septics I wasn’t sure if I was pulling up matter direct from the septic tank itself and so stopped the process. I’ll try the product you suggest next whilst researching local septic services as as you suggest may ultimately be worth bypassing old and installing new… but one step at a time.

thanks again for your time and knowledge 

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(@jonesdn2020)
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@genki Fine black particles reminds me of our latest repipe project. The house had a cast iron sewer system that was 50 years old. The plumber kept using a snake and I finally told him we needed to run a camera down the line. We discovered there was virtually nothing left of the cast iron and it had been leaching into the soil under the house. This was causing foundation cracks.

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(@genki)
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@jonesdn2020 thanks… let’s hope not eh, but will find out soon I guess 🙂

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(@genki)
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@thomasribatejo by the way… as a side.. once we bought the property and knowing we now proudly owned a septic tank too (we are easily pleased) we headed off to the supermarket to try and purchase all sorts of septic tank cleaners and friendly household products such as washing machine tablets, shower gel. With the prevalence of septic tanks we expected to find an entire section for these products or a least a logo or icon on the product to show it was safe to use with septics. We found zero products for septics or that are septic friendly. Am I doing something wrong? What should I look for if not quite as bold as I expected?

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(@thomasribatejo)
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@genki boa pergunta! So, partly it depends on the supermarket; and then sometimes the small print.

Eco ranges are pretty much fine. Leclerc and Auchan are best for these; Intermarché variable; Continente improving; the rest, pretty useless. Own brand eco at the first two are good, and avoids the high prices of fancy brands.

For things like Destop, they say they're OK for septic tanks in the small print (or don't!). Basically, avoid chemicals, bleaching agents, artificial scents, etc wherever possible, and the lowest frequency of what you do need to use (eg loo cleaner, drain cleaner).

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(@genki)
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@thomasribatejo Thank you... I've seen the Eco range products and so we will head for those for our household goods. Assume that Septic tank treatments such as Destop or like this ( https://www.amazon.es/-/pt/gp/product/B00KGDXA12/ref=ox_sc_saved_title_3?smid=A1AT7YVPFBWXBL&psc=1) is not a common product for supermarkets then.

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(@thomasribatejo)
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@genki The Destop is widely available (and own brands in the same colour bottle - the purple is easily spotted - I see Leclerc, Auchan, Continente, etc all do it, though may vary by store size).

I haven't spotted the capsules, but then we get no odours from our (soakaway) septic tank so have not needed to alter its chemical balance proactively, just clean pipework to it, or sanitary ware.

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