How to: Off-Grid House - Water and Sewage

Living in an off-the-grid house doesn't mean that you have to compromise on comfort.
When I first thought about buying a house (remember, I was 20 at the time), I had the preconception of having to live like I saw in the rural areas of the country, with a well and toilet outside of the house. I knew that there were some improvements but I had no idea how that would be possible. So I have studied the housing and the market for land properties, soon it made no sense to even think of buying a house which was connected to the services. This was mainly because of the price. So I have devised a SWOT to find out if it was worth it. (find out what this is from a fellow Steemian). Then, after I was educated on the advantages and disadvantages, I could go further with the plan.

Source

What are the needs of the house and what can be provided off the grid?

First of all you need water, most can be dirty, a part must be clean and a small amount must be potable. Throughout this article, I will use as a basis of calculation the needs of a small family: Two adults and two children but you can calculate your own needs using my ideas. I have actually devised my own - unofficial :) - unit of measure (the minuteFaucet) since I have chosen a faucet that allows a predefined amount of water to pass through, which is 10 Liters per minute. I will get to this later.

The average daily water consumption stands like this:

Reason	Purity	Time
Irrigation	unfiltered	30 min
Car wash	unfiltered	5 min
House water	filtered	90 min
Drinking water	pure	2 min

Basically, most of the consumption comes from either irrigation which is dependent on the size of the land owned and the house water which consists of two showers per day, water to wash dishes using a dishwasher and water for the washing machine. If both of those machines are highly efficient, then the consumption is negligible.

Presuming that everything will run at once, we can calculate that the peak consumption would be around 40-50 liters per minute and a total consumption of 1300 Liters (343 Gallons).

Getting your own water

The basic way to get water on Earth is to drill for it, presuming you don't have a waterfront property or you are not building your house on the floodplains, which is something I don't advise due to water coming in through the windows and doors and not from a faucet :D

There is a website which centralizes all of the satellite data for the aquifer depth and resources so be sure to check it before embarking on the journey of drilling. The drilling company also has access to local aquifer data and can even make some suggestions.

Drilling for water is a simple process but can vary in cost depending on the materials used and the depth of the borehole. If you live in a residential area which has never had another source of water than from a borehole, than I can advise you to drill to the second aquifer. The first one is probably compromised by other drilling or accidental spills.

An aquifer is a layer of water-permeable rocks that traps groundwater. Sometimes rock layers break or are pushed outward and they break forming streams and springs, but under the first aquifer there are more layers of subsequent rocks and water, which are not exposed to the same factors. Drilling to the second or third aquifer is thus a good way to minimize pollutants and reach cleaner water. Also drilling to an aquifer that is not tapped by others means that in case of extreme drought you will still have access to clean and plentiful water.

Drilling process

Modern drilling is automatized and usually very fast. It consists of a pneumatic drill in the back of a truck. It digs into the ground and a layer of sand and gravel is deposited on the outside of the big drill, then a filter tube is lowered into the hole, usually sections are being added while the hole is being drilled. I won't go into many details about the process, although it's very interesting to see and analyze. The tube is PVC and the filter is built into the tube, thus making sure that the water is not contaminated by the other aquifers.

A pump is lowered into the newly created well and will pump all the mud and impurities out, until the water becomes clear. Then the final pump is lowered and it can be included in an automated system to provide water for the house. The diameters of the well should also be taken into account as it doesn't have to be too wide for the selected pump, maintaining the cost low but it shouldn't be too narrow as to limit the selection of pumps. The pumps can be single level or multi level, depending on the depth of the well.

Piping

The piping of the house can be made of Polypropylene Random Copolymer or PPR . They are hard pipes made of very resistant polymers. Some have aluminium inserts (the ones for hot water) or can be made with extra fibers addition (colored green). It has many advantages over metal piping (galvanized iron or other cheap allows). There are better iron alloys but they are much more expensive than PPR so we are only going to analyze the best quality for the price:

• PPR is much more lightweight than metal piping.
• PPR has a much smoother internal surface.
• PPR pipes are not susceptible to corrosion.
• PPR pipes are connected by melting the ends and bonding them to one another. No leaking and no other sealing material, solid or liquid needs to be present on the threading.
• PPR pipes are flexible, which means that torsion and curving is tolerated and even encouraged, since it will reduce the number of straight angle fittings which usually reduce flow.
• The prices of PPR are usually lower than metal counterparts.

Filters

As I have said before, in order to be economical and keep the energy consumption low, you can use unfiltered water for usual needs like watering the greenery or garden or washing the car. For the other activities like washing (yourself, dishes or clothes) or drinking, you should use filters. What kind of filters would you need and how to find out. A basic set of filters is not expensive, so you could just buy them all, but for the most advanced needs or if you plan on drinking the water then you should do a microbiological test. It doesn't cost a lot (30$) and you get the specs of your drinking water, they might even recommend what filters to use.

^{Example of basic water filters in multiple sizes, connected by PPR fittings. Source}

Among the basic filters you would need:

• PE mesh filter - this is the cheapest washable filter, doesn't need replacement and it filters everything bigger than 50 or even 20 microns. Protects against sand, rust and suspended particles in water.
• PVDF mesh filter - this is another washable filter, filters everything bigger than 0.1 microns. Removes bacteria and all the other sand, rust and suspensions but it is much more expensive than the other.
• Activated carbon - this type of filter is used for 6 months or until the specified debit of water has passed through it. It filters smells and taste, but they can get clogged easily if not preceded by one of the other types of filters.
• Cotton wrap filter - filters most particles between 5 and 20 microns.
• Polyphosphate filter - anti limescale filter, used mostly in non-potable installations, the resulting water is not usually potable, but it might be a cheap way to wash your car without blasting it with fine particles of limescale or other similar deposits.

These filters are very cheap and can be replaced without much problem by any user. Additional filters might be used for further reducing the limescale of the water and to prevent limescale deposits on the appliances and bathroom fixtures.

The water analysis made by a lab might highlight the existence of hard water. This is usually occurring in areas of high mineral deposits. When the aquifers pass through a layer of calcium or magnesium the water washes off the deposits and gains calcium ions.

A water softener usually uses ion exchanging resin to isolate and dismiss those calcium ions. The resulting water is softened by an amount or fully and the systems can even control the hours of operation. This is a more expensive system, it need physical sodium tablets recharges and once every few years, the replenishment of the ion-exchange resin. While this system needs a technical room and can get quite bulky (the size or a single door locker), its benefits can easily overwhelm the disadvantages. The type of water softener I use has a smart control valve that auto regulated the quantity of resin and the quantity of sodium tablets it uses, so everything is done without my supervision. The hours of resin regeneration (once a week) is planned late on Monday nights, right before dawn, and it takes the system out of commission for 20 minutes. If water is needed in this time, a valve is automatically triggered and it bypasses the system.

Example of water softeners with the automated valve, from the supplier I have used to buy mine. Used with permission. Source

The final level of treatment is the use of UV lamps or inverse osmosis to make potable water. The prices vary depending on the quantities of pure water sought and can vary from 50$ (strictly for daily drinking water and water to use in food) to $1000+ for the ultraviolet light. In the case of a small inverse osmosis system, a semipermeable membrane is used to filter impurities from the water. Sometimes though, this membrane actually also filters minerals that the body expects to find in the drinking water so having another source of those elements is considered useful. Some suppliers also offer remineralization tablets, but I don't know how much of it is marketing and how much is actual science.

In the case of the UV lamps, a transparent glass coil is wrapped around a powerful UV lamp, encased in a UV protected case. UV light kills off bacteria and most of the viruses so the resulting water is safe for drinking. It is more expensive than the inverse osmosis but generally seen as safer.

Automated system

For streamlining the process, a number of techniques can be used, but the most common, cheap and useful is the use of an expansion tank, along with a submerged pump and a sensor.

The most important part of the system is the expansion tank and pressure valve. Inside a metal casing there is a rubber membrane which is compressed by air around it. When the pressure valve, pictured in orange, senses that pressure inside the expansion tank is below a preset value, let's say 2 bar or roughly 2 times the pressures of air outside, it sends an electric signal to the pump controller. This starts the pump which starts to inflate the membrane inside the expansion tank, compressing the air around it.

When the expansion tank is full - the pressure of air exceeds a preset value, let's say 6 bar - the pressure valve stops the pump. The pressure is visible on the gauge, and the water inside the expansion tank is now prefiltered. We now have the irrigation water ready to use. When a faucet inside the house is opened, the water starts to flow and the pressure will reduce, repeating the cycle.

The water then passes through the water softener where it is washed through a tank of ion activated resin, removing calcium and magnesium particles and then can reach the showers, dishwasher and bathroom sinks. If one of the faucets connected to the pure drinking water is opened, then the water will pass through the inverse osmosis or the UV lamp and will be purified.

But what about the sewage?

To treat the sewage from the house, a two step process is being used. The first step is the separation of hard residues from the water followed by the removal of soaps, oils and other surfactants and then sending the clean water back to the soil via percolators, buried before at a safe depth to prevent resurfacing of the water. The second step is the processing of the hard residues, through the process of anaerobic fermentation, using a special mud. This further separates water from the residues and also produces a small quantity of biogas. There are cheaper systems which mandate regular cleaning of the mud (every 6-12 months) or some other systems which claim that no cleaning of the mud is necessary, although the mud should get replenished every year or so.

Conclusions

There is much more to say about this subject, this barely scrapes the surface of the ways to minimize the carbon footprint of your house and have a self-sufficient house on the long term. If you are not living in a very densely population area or you are just planning to move far away from civilization, it doesn't mean that your comfort has to suffer. The research in this field is constantly improving and allows for reduced cost and there is a very rich market of solutions to choose from.

I hope I have helped you understand the processes a bit and that you have more courage to start your own project. If you have any questions don't be shy to ask. I couldn't catch everything in one (not so) little article.

Sources and further reading:
My own documentation and implementation between 2010 to present day. It's my pleasure to gather all this info I have and never wrote down and wrap it together here for your future use.
Made my own figures and graphics.
Further links to support my claims
https://en.wikipedia.org/wiki/Expansion_tank
https://en.wikipedia.org/wiki/Activated_carbon
https://en.wikipedia.org/wiki/Ultraviolet_germicidal_irradiation
http://cv-water.ro/en/residential-segment/intellibio-wastewater-treatment-plant-residential-applications/
http://cv-water.ro/en/residential-segment/drinking-water-treatment-technology-for-household-use-intelliwater/#1490872439865-353019e0-7862