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Cabin Water Systems

tiny house water system rainwater collecting

Water resources

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Tiny house plumbing is a big issue to solve when you’re moving into your dreamed RV, but also in other cases when you’re building a small cabin or cottage as a vacation spot, etc. We already wrote an article about heating options and today we will concentrate on tiny house water systems including some off grid living solutions.

There are various options of water resources to use in your small house or wood cabin. The most common in these case are probably the underground water sources such as connecting to the public water main or constructing water wells. These are more used in distant and non-residential areas where you can also take advantage of alternative sources of water such as rainwater, that can be filtered or cleaned with chemicals, or sea water, which you can desalinate.

tiny house water system public main
Connection of a house to public water main
  • A. Property of water authority
  • B. Property of building owner (except the water meter)
  • a. Valve
  • b. Water meter
  • c. Filter
  1. Public mains
  2. Ground closing valve
  3. Water metering system
  4. Water meter box
  5. Underground water supply to building

The biggest of natural water resources is ground water: water, which comes from rain and soaks into soil, filling in beds and other gaps or openings in the ground. It represents majority of all the fresh water in the world. The easiest method to access water is, if there is the opportunity in your area, to connect to public water main, which brings water from distant reservoirs and is subject to strict hygienic rules and monitoring. But it requires a building permit and that can become an obstacle in cases of tiny houses.

tiny house water systems
Diagram of traditional domestic water system
  1. Expansion tank
  2. Control unit
  3. Connection fittings – shower / basin / sink
  4. Main closing valve with drain
  5. Water source – underground water / tank
  6. Pump

Types of wells

Beside public water main, there are also off grid water systems, most common various types of wells.

Hand dug wells

Historically the oldest are hand dug wells, which are now used mostly in rural areas and developing countries, as their construction and maintenance is cheap, do not require any heavy machinery and it is possible to get the water even without water pumps. These wells are dug with shovels beneath the water table level, usually around 3.5 – 4 m deep (approximately 10 – 15 ft) and lined with stones brick, wood or in modern times mostly concrete rings to consolidate the shaft in such a way, that the lining continues higher forming a well above the ground in order to protect the water from contamination and people from risk of injury. Hand dug wells have a large diameter, bigger than for example drilled wells, and they are able to extract from shallow underground water level and also less permeable materials. But they are subject to risk of colliding with wells nearby or contamination from surrounding surface or sewage, as there is no solid steel casing. Very similar to hand dug wells are shaft wells, except they are constructed with mining technique and use pumps to access the water.

types of wells shaft well
Types of wells: Using shaft well as a water source connected to a house
  1. Control unit
  2. Expansion tank
  3. Cover lid
  4. Landscaping hiding the well mouth
  5. Clay soil
  6. Underground water level
  7. Pump pipes
  8. Power supply for pump
  9. Pump
  10. Concrete rigs
  11. Gravel
  12. Sand and gravel

Driven wells

Another from types of wells are driven wells. Their construction is made by a small diameter pipe driven by hand or with help of power tools into unconsolidated ground – water bearing sand or gravel. At the end of this pipe a screened well point is connected for bottom of the well to filter out sediment. Driven wells are simple and quite cheap to construct, but do not have sealed casing, so they may be subject to contamination as well. They also extract water from shallow depths with pump, but can be deeper than hand dug wells – up to around 9 m (30 ft) if they are dug manually and 15 m (50 ft) with power driver.

tiny house water system pump
Water pumps to get water from wells, tanks and other storage facilities
  • A. Wind pump, B. Manual pump, C. Solar pump, D. Electric pump
  1. Wind wheel
  2. Pump rod
  3. Discharge
  4. Tower anchor
  5. Pump
  6. Aquifer
  7. Water outlet
  8. Water suction line
  9. Force rod
  10. Solar panel
  11. Pump control unit
  12. Pump
  13. Water tank

Drilled wells

Last to describe are drilled wells also called bored wells, large-diameter wells drilled with augering, rotary or cable tool drilling machines that are usually mounted on large trucks or trailers and able to drill even through solid rock. Thus drilled wells access water from much bigger depths than hand dug or driven wells – their usual depth is from 3 to 18 m (10 – 65 ft), however they can go as deep as 900 m (3000 ft). In order to avoid collapse or contamination of the water a casing is put around the well shaft. The casing is made of steel pipe or plastic/PVC segments, usually at least 6 m (20 ft) long, welded together and sealed around with grouting material, such as cement or bentonite clay, therefore the water is protected from contamination. Some machines are installing is simultaneously during the drilling and construction process, while in other cases it is placed after the process are finished. At the bottom of drilled wells is a screening device or filter device or an open bore hole, depending on the particular formation, to let the flow of water into the well.

drilled tiny house water system
Types of wells: onnection of drilled well (bored well) to a house
  1. Water connection
  2. Power supply cable for pump
  3. Concrete seal
  4. Perforated shoring
  5. Submersible pump
  6. Sludge catcher
  7. Lid
  8. Concrete ring
  9. Closing valve
  10. Backfill
  11. Underground water
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Rainwater harvesting

Rainwater harvesting is becoming popular part of sustainable living. Rainwater is collected into tanks and stored to be re-used for household activities that do not require drinking water, such as cleaning, laundry, heating, gardening or flushing the toilet.

Rainwater collection systems

We distinguish between land-based and roof-based rainwater collection systems. Land-based rainwater harvesting means collecting water in pounds or impoundments before it is taken away by stream or river and this water is much more prone to contamination. Roof-based systems collect the water before it hits the ground into tanks placed on the roof and then lead it to storage water tanks. This water is much cleaner, although even then it must be properly treated and filtered if you wanted to use it as drinking water. In this case of rainwater collection it would be also worth considering what types of materials to use for the roof itself and keeping in mind that steep slope makes the system work more effectively.

tiny house water system rainwater collecting
Diagram showing how rainforest harvesting system works
  1. Tank
  2. Pump
  3. WC
  4. Car wash
  5. Garden
  6. Overground – surface storage tank
  7. Underground tank

Rainwater storage tanks

There is a variety of systems for rain-water harvesting, from small and very easy to install to more developed, automates ones, which require a professional set up. Regarding the storage water facilities, there are two most common types, at least in case of the simple systems possibly suitable for your tiny houses or small cabins: free standing and underground water tanks. Free standing water tanks are affordable, easy to manipulate and do not require any ground work. But there is a risk of sensitivity towards weathers conditions – they may need to be emptied during winter and can heat up and accelerate the water biodegrading during summer. Also due to constant exposure to outdoor environment their life span is shorter and they are not very visually pleasing. Most of this can be prevented with right choice of materials and insulation, but that will on the other hand make them more costly.

Various types of storage water tanks for rainwater collecting
  • A. Surface water storage tanks
  • B. Underground water tanks

The second option for water storage are underground water tanks, which do not have issues with weather and are thus more durable. They also have the advantage to be placed in dark, which is not favorable for microbes and algae. On the other hand they cost two to three times more than the surface water tanks. In both cases it is important to ensure all facilities are designed to reduce risk of potential contamination and their size is large enough to capture as much rainwater as you need, especially if you considered using rainwater harvesting as your primary source of water. Although it is always advisable to have a back-up one, as weather can be unpredictable.

Pros and cons of rainwater harvesting

As well as other water resources, rainwater harvesting also has its pros and cons. It provides clean, cheap and independent water supply that can supplement the main one in case of any problems, which is often used especially in developing countries. The installation and maintenance of the simpler systems is easy, good option for example for areas with ground difficult to penetrate, and it helps to prevent floods and bank erosions. If people use too much groundwater resources, their level decreases, so using rainwater instead is definitely beneficial, especially in areas with limited water sources. Collecting rainwater also lowers / minimizes one dependency on public water services, although it can be actually incorporated in the public mains, in which case it brings advantages of need of smaller amount of clean water in the distribution system and less rainwater in sewer system.

Water heaters

Among main decisions to make when it comes to water heating in your tiny house is to choose between storage or tankless water heater and a heating source.

Storage water heater

Traditional storage water heater stores preheated water in an insulated tank to be used whenever someone opens a tap or does the laundry. The tank refills automatically to always have enough hot water ready and is heated either with electricity or gas burners. Storage water heater requires smaller initial costs, it is simpler and easy to install, maintain or repair. However it cannot be placed outside, its size is bigger and life span shorter – almost half of that of tankless water heater, approximately around 10-15 years. Then even despite the insulation there is always some heat lost through the tank walls creating stand by losses and that together with heating the water automatically regardless of your actual needs results in higher utility bill. Also there is a given amount of water that can be heated in one hour, depending on particular type of heater, meaning you can run out of hot water and be forced to wait, if your needs exceed it.

water heating options
Different types of water heaters
  • A. Gas tankless heater
  • B. Electric tankless heater
  • C. Electric storage heater

Tankless water heaters

Tankless heater is also called on demand water heater, because it heats the water on demand rather than storing it. So when you turn on the tap, cold water runs through a pipe into the tank, where it is heated. This means you cannot run out of hot water and there are no stand by energy losses, which makes tankless water heater more energy efficient and cost efficient in the long run. However there is limited flow of the water and a multiple using, such as taking a shower while the dishwasher is on, may be a problem. Although gas water heaters provide bigger flow than electric ones, the most reliable solution would be to have more tankless heaters connected in parallel or installed directly at the point of use. It also takes up less space, some of them can be placed outside as well and it lasts longer – approximately 20 years or more. On the other hand the installation or repair is more complicated and expensive, especially if you want to change from the traditional storage water heater, because it is a complex system consisting of more parts. That also means they require more maintenance and have a bigger risk something will go wrong, for example due to extreme weather conditions.

tiny house water heating solar panel
Diagram showing the process of using solar energy to heat the water
  1. Thermal solar collector
  2. Pump unit
  3. Expansion tank
  4. System regulator
  5. Thermostatic mixing valve
  6. Hot water storage tank
  7. Additional electric heating (cartridge)
  8. Water intake

Water heating fuel

Regarding the source of fuel for your water heating, there are two main options. Electric heaters are smaller, cheaper and easier to install, but the cost of electricity consummated for your water heating is going to be quite big. Gas heaters, usually propane heaters, take up more spaces and are more complicated to install but the running costs are lower and they also comply with off grid living. That brings us to entirely alternative source of energy that can of course be used for your water heating as well, solar thermal connectors. Important thing is their location. You need to find a space most exposed to the sun, where you can at the same time access the, easily to be able to keep them clean in order to be the most efficient. Some sources also recommend keeping them in cooler space, such as for example ground rather than roof, because that is another way to raise their efficiency. Figuring out size of the panels is also important, but during the summer they may be able to supply your entire hot water consumption.

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