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Cost to install a Septic system


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I think the cost will depend upon what, exactly, is planned.


In years gone by, Costa Rican "Tico-style" homes have had "black water" systems that served only the toilets and grey water systems that served everything else -- sinks, showers, laundry, etc. It's actually a pretty good set-up.


In the past (and maybe still today), the design of the black water system was simply to dig a pit, run the toilet drain pipe into it, and cover it with a concrete cap. The liquids dissipated downward and sideways through the soil. When the pit was full of solids, a new pit was dug and the drain rerouted. This "system" has not been legal for many years.


An "upgrade" to the simple pit design has been to use two sections of precast concrete drain pipe (maybe three or more feet in diameter) stacked on top of each other to form a tank with the drain running into it. This approach, too, may or may not be legal. The question, of course, is "Who's checking?"


A modern black water system includes a solid tank of block, fiberglass or plastic, or maybe the drain pipes referred to above with a gravel-filled drain field with perforated pipe to carry away and dissipate the liquids.


You can see, therefore, that you have to define your terms. Just what sort of black water system will you be building? And what sort of grey water system?


In the U.S., modern building codes require that there be an alternative drain field site on the property where a new system could be installed if the original one fails. It's good to keep that in mind.



And then there's the matter of the grey water. Many Costa Rican homes simply drain their grey water into the ditch in front of their property or elsewhere. The environmental considerations associated with this practice are an open question. While it may seem distasteful, one must ask, "Where are all the dead bodies?"


An alternative to using the ditch in front of the house is to build an underground grey water system. Depending on the space available, such a system could include a holding tank and drain field similar to a black water system or it might simply involve a gravel-filled drain field.



The only meaningful answer to your question will have to come from whomever designs and builds your system(s). There are too many variables (location, design, size, soil type, material costs, etc) for anyone here to be of much help. You need to determine what is to be built and get bids.

Edited by David C. Murray
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Here is a site I've come across in my internet travels that may be of interest. (No experience with them, but will call them for my next project)

You can also download basic plans and installation here.





(The simple grey water systems I've see constructed lately generally include a simple concrete grease trap as well. You will see a modern version of this in the above link)

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Costs, right. Costs for parts you can find in the above link and at your local ferrerteria.


Backhoe: if accessible, 20-25 mil / hr in my area (Depending on terrain and the system you choose, probably about 2-3 hours. )


Constructor: 2.5 mil / hr


Helper: 1-2 mil / hr


(again these are the labor costs I find in my area)


2-3 Days total time.


Consider a workers INS policy. just in case. If this is permit work I would expect the local muni to require it.

Edited by Criollo
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Another option:


1. Two men dig a hole that will fit


2. Two 36" concrete drainage pipes (like used for rainwater culverts) Set them in the hole on top of one another.


3. Add some cement and 4" pipe. Buy a cement top made especially for this. It has a rebar handle in it so can be removed for cleaning.


4. Make an appropriate drain field -- the simplest way to do this is to dig a wide trench, line it with castoff building materials such as pieces of a tin roof that have been cut off, run a 4" pipe - perforated when it gets to the drain field - and cover that with any remaining pieces of tin roof or rocks you can pick up along a back country road. Cover all that with plastic and then return the dirt.


In most cases, you will need to have a permit from the municipality and that means doing the construction to their specifications - so it's really hard to say what is something that will work everywhere.


You will definitely need to provide Caja and insurance since they will check on this.


Make a separate "dry well" for your kitchen and shower and sink waste. Don't put this into the septic tank. The ONLY reason to do that is to conform to some regulation from the municipality - but I doubt that they would require that.

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Criollo, have you allowed for a gravel bed for the drain field and perforated pipe? And won't how much of both depend upon soil conditions?

It depends on the system you choose. Not all systems require a drain field. I suppose we could mention an engineering site exam and perc test as well. You can find diagrams and installation instructions at the site I posted above. Basically the same as eleanorcr described, difference being plastic tank or concrete pipe (which I used in my last two house constructions) There are many others available. Once you have your system chosen and designed and material list in hand you can get a better estimate at your local ferrerteria. Shop around if possible.

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Notice, please, that no one has tried to respond to the basic question posed by the originator of this thread -- "What will a system cost?" That's because no one can give a meaningful number without knowing much more about what will be required and what the local conditions are and that was my original point.


I mean no criticism toward anyone. It's just that different locations and conditions call for different solutions at varying costs. To pose such a vague question reminds me of a similar question posed a couple of years ago ("What will a retaining wall cost?"). Without much more detail, any answer would be meaningless.



Edited by David C. Murray
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In addition to the time and labor estimates I previously mentioned in response "to the basic question posed" here are few material costs gathered from ConstruPlaza that may be of assistance.


Tubo PVC Sanitario (SDR50) 4 pulg (100mm) 6 metros 7.220,00 mil

Tubo concreto reforzado 30 pulg Con hueco (762mm) 24.961,00 mil

Fosa Septica 1100 Litros 133.240,00 mil

Trampa de grasa rectangular tapa concreto 8.390,00 mil

Tubo PVC Drenafort perforado 4 pulg (115mm) 6 metros 9.433,33 mil

The website I posted also offers price estimates.

Edited by Criollo
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