Tiny House: Pressurized Water System

Tiny House: Pressurized Water System

July 9, 2017 Categories Tiny House

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One of the many conveniences about modern living that people often take for granted is having clean, running water. I’ve lived in multiple places during my life where running water wasn’t a luxury that was available. Even though I hope to live in my tiny house as more of an off-grid thing, I still want running water. It’s simply a delight to have.

My system is made up of a few different components, starting backwards:

Filtration System

Since I’m designing my tiny house to be able to maintain itself without connections to the grid, I decided a good idea would be to build in a water filtration system. I did this for a few reasons:

  • I don’t know my source of water. Ideally it will be from a well or city water, but the water could come from anywhere since I have a holding tank and the options for filling it are only limited by one’s imagination.
  • Better tasting water. The filters will help to remove bacteria and other contaminants, such as rust, chlorine, and sediment.
  • Saves money. Even with the two-stage filtering, it only costs about $40 per year to replace the filters. It’d cost nearly six times that amount to drink bottled water.

The system is pretty basic and only cost me $60 to set up. I bought two DuPont Whole House Water Filters to create a two stage system. The first stage does a pre-filter using a Poly Block Cartridge and then the second stage uses a Carbon Wrap 2-Phase Cartridge to really get the water clean. Both of the filters can filter up to 15,000 gallons of water and I’m pretty sure I’ll never even come close to that limit before I have to replace each filter.

You could easily spend a lot more money to build a more complicated system, but chances are I will be out in the country living on water from a well and I’m only concerned about basic filtering.

Pressure Tank

I decided to install a WaterWorker Well Pressure Tank for two reasons:

  1. To help reduce the amount of times the water pump has to kick on, which will hopefully increase the life expectancy of my pump.
  2. To increase my water storage capacity. The pressure tank I bought says it holds an additional 14 gallons of water. Frankly, I’m skeptical it could hold that much water but I’m confident it can hold more than a few gallons.

A normal RV is likely to have a water pump followed by an accumulator. The main job of the accumulator is to store a small amount of pressurized water to provide a constant flow in between the pump’s cycles. When you turn on the faucet, you get a steady stream of water just like you would in a normal house.

A pressure tank does the exact same thing an accumulator does, only on a bigger scale. They typically hold several gallons of water, which means you can run the faucet for a lot longer before the pump will need to kick on. Even if you didn’t have power, you could still run the faucet because the water in the tank has already been pressurized.

With the pressure tank, I also bought a Tee Kit and a check valve. The Tee Kit comes with a pressure gauge, pressure switch, relief valve, and a drain valve.

  • Pressure gauge. Allows you to see what the pressure in the tank is. A typical home has water pressure around 40-45 PSI.
  • Pressure switch. Automatically turns the pump on and off when certain pressures are reached.
  • Pressure relief valve. If the pressure gets to high, the relief valve will open to reduce the pressure.
  • Drain valve. Can be used to manually drain the tank. Or you could hook up a garden hose and water the lawn. Your call.
  • Check valve. Only allows water to flow in one direction. The check valve is important to install so that you don’t have the pressurized water from the tank backflowing into your pump. Water should only flow from the pump into the tank.

Water Pump

The water pump is obviously the most important part of a stand-alone system. It’s job is to take water from the holding tank and pump it into the rest of the system.  Since most of my tiny house is designed to run entirely off of DC power, my SHURflo water pump is no different. On the inlet of the pump, you’ll also want to attach a strainer to filter out any debris so you don’t damage the pump.

I used the exact same water pump when I built my campervan and never had any issues with it. It produces plenty of pressure and can pump three gallons per minute.

Holding Tank

I bought a relatively small holding tank, as it only holds 20 gallons. Since my entire water system is housed under my sink area, I tried going with something that wasn’t too large but also wasn’t too small. Being that I live in a cold weather climate, having the tank outside of the house itself isn’t really an option. Obviously if you live in a warmer climate, you could go with a bigger tank and install it under the house or elsewhere to save a little room.

Water Inlet

Lastly, we have the water inlet. I expect my main usage of the water inlet to be for filling the water tank. However, there’s also a connection for attaching a garden hose to which would allow me to bypass my entire pressure system and connect into my water system directly before the filtering stage. So, whether I’m connected to city water or using the holding tank water, all of my water will still go through the filtering stage and be crispy clean.

8 thoughts on “Tiny House: Pressurized Water System”

Raphael · April 8, 2018

Hi there,

Thanks for your posts, they have been helpful in planning my own off grid water system. The one thing I am wondering about is the wiring of your pressure switch. It looks as though you have everything hooked up DC. In researching square d product information, I can’t find anything about running pressure switches on 12v. My understanding is that the switch is just a set of terminals and so it should not matter if its relaying 12v or 240v, as long as amperage is not exceeded. Im I correct in thinking that you are running the pressure switch on 12v? How is it working? Any issues to report?

Thanks a bunch,

Luke · April 8, 2018

Yes, I wired it up to a 12V pump and haven’t had issues with it. The switch itself is activated based on pressure and merely opens or closes the circuit. Like you said, it’s just a set of terminals.

I’ll admit, using the pressure switch and tank is likely overkill. It takes up a bunch of extra space and I’ll likely drop the extra tank and switch and just use the pump with a small accumulator instead.

Christopher Thomas · June 7, 2018

Could I attach my hose directly to the water pump and bypass the need for a water tank if I don’t plan on being off the grid, but don’t want to dig and put in official plumbing?

Luke · June 17, 2018

If you’re not going to be off grid at all and have access to a regular (pressurized) garden hose, you don’t even need the pump. I have a pump and a tank because I don’t have a regular water hookup.

meghan · August 28, 2020

Hey, Luke. This article was super helpful. We just bought a used tiny house and are having some issues with the plumbing. I think something got damaged in transport from NY to MN. Anyway, wondering if you might have ideas about why when the pump is running, water is draining from the tank at a pretty high speed? We can still use the water, but a ton of it is just draining out the inlet. The water pump will always run making me think it’s a pressure issue and it’s not getting up to enough pressure. But, we’re also having an issue that when we attach the hose, water squirts all over the place. We are able to fill the tank, but again, so much water spilling out of the inlet. We did put a new washer in there. And I bought a new inlet, but we haven’t tried to install it yet because the inside plumbing is nice and hidden and we don’t really want to have to pull the whole cabinet out to reach it. Thoughts? THANK YOU!

Luke · August 29, 2020

You have water coming out of the inlet? Sounds like a valve is open that should be closed. My inlet has two ports – one fills a water tank in the house (which the pump is connected to) and the other is meant for a hose to be connected to (doesn’t need a pump since the hose has pressurized water). I have valves installed on mine so that I can shut off the “hose” inlet when I’m using the tank, otherwise water would do as you describe and go out the inlet. If I had a hose connected, then I would do the opposite and close the tank side and open the hose side. If a hose was connected, I close the tank side to avoid the pressure from the hose pushing water through the pump in the wrong direction.

If you have a similar setup, make sure only the one in use is open.

Chris · November 15, 2020

Luke, what size PEX did you use for your setup? I appreciate it

Luke · November 16, 2020

I used 1/2″ because my system is extremely small and only has a few feet of line. It’s not like a normal house that would use a 3/4″ trunk and 1/2″ branches.

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