Tiny House Water Systems – Part 2

This is the third post delving into the various systems in a tiny house. For the others, please see the links at the bottom of the introductory post, here. Note that I originally planned to have this one post encompass water supply systems, water heating systems, water waste systems and winterization concerns; however the post ended up being so long that I decided to break it up into two posts: Part 1: covering water supply and water heating systems and this one, Part 2: covering water waste systems and winterization concerns.

 Waste Water Systems

Skara Brae by Wikipedia editor Wknight94

One of the common, yet often unspoken problems that we run into in tiny houses is dealing with our waste water. People have had to deal with waste water forever, and it has resulted in sewer systems known to have been built as far back as the Neolithic settlement of Skara Brae on the Orkney Islands in around 3180-2500 BC.  So it is no surprise that Tiny Houses need to have some means of dealing with waste water.

Black Water and Grey Water

There are two types of waste water that need to be dealt with, commonly referred to as Grey Water and Black Water. The differentiating factor is the type of waste carried in the water. Black Water contains fecal matter, and typically originates in the toilet. Grey water does NOT contain fecal matter, and typically includes waste from the sink drains, from showers, and dishwashers.  Standard plumbing systems combine both types and treat it the same, but there is a growing movement to separate out the grey water and only send the black water into the septic or sewer system, using the grey water for purposes like watering the lawn, reducing the amount that needs to be treated by the septic system or the utility company. If you decide to go this route, there are a lot of reference sources out there to help, but the decision needs to be made in the early part of the design stage. You also need to verify with the local codes or health department as to what restrictions they impose on designing for the use of grey water. You don’t want them to forbid you from using your system (under threat of fines) or make you rip it all out, redesign and rework it.

Yet as Lloyd Alter recently pointed out in an article in the UK’s The Guardian, the way that we deal with Grey and Black water waste is inherently wasteful and, quite honestly, somewhat unhealthy. It is an interesting read that may help inform your decision.

Toilet Options

Water closet, loo, throne room, outhouse, littlest room in the house, bathroom. All of these are synonyms for a private location in which to use the bathroom. there are a number of different options available to tiny house inhabitants, one of them will be right for you. The easiest to deal with is simply not to deal with it. Rather than allocating precious space in your tiny house for a toilet, you can always plan to make use of the toilet facilities in a nearby house or restroom. Many people have gone this route with successful results, but it is not for everyone.

Simplest option
Simplest option

The simplest to deal with is a sawdust composting toilet, based around two 5 gallon buckets. One bucket is used to hold dry sawdust, the other catches the waste. A nod to comfort is made by getting a pool noodle, cutting a slit in it, then trimming it to fit.     After using, you simply add a layer of sawdust to help contain the smell and start the composting process. It requires emptying on a regular basis into a composting bin set up outside, and proper care needs to be taken in dealing with the waste and composting process.

The Humanure Handbook 3rd Edition by Joe Jenkins

The best resource available on the topic is “The Humanure Handbook” by Joseph Jenkins. Joe began writing the book as a mater’s thesis while attending Slippery Rock University’s Master of Science in Sustainable Systems program in the early 90’s. The thesis adhered to the staid, dry (boring!) conventions of academic papers, which did not satisfy him, so he translated it into normal English that a typical person can understand and self-published it. Now on the 3rd edition, the concept has gained widespread attention and acceptance, and has been translated into 15 languages.   Of course, composting toilets need not be as basic as the option shown above. Joe also sells a starter kit through his website called the Loveable Loo. lvoeable_loo Of course, you can also build your own customized version, which is limited only by your imagination as to the luxuriousness available.

 Camping Toilets

Camco 41541 Portable Toilet - 5.3 gallon
Camco 41541 Portable Toilet – 5.3 gallon

Another option available is a camping toilet. These are normally square and blocky, having a holding tank beneath that will require regular emptying, and the more people using it will increase the frequency at which emptying is needed. Limited storage space you know. 🙂 There is no covering with sawdust required, as they normally have a trapdoor between the bowl and the holding tank which serves to limit the amount of odor that escapes. All of the above options are ones that allow your tiny house to be mobile.  However, the RV market has come up with a solution that allows for larger capacities, which is to build in a larger holding tank beneath the floor with a drain used for emptying at a campground dump station.  These are also typically sized to handle capturing all water waste from the sinks and shower.

Thetford Aqua Magic V RV toilet, designed to be mounted above a holding tank

A number of manufacturers make a toilet that is designed to mount above the holding tank, complete with a trap door mechanism and a water seal to help with odor control. The downfall of all of these portable solutions is that they need to be emptied on a regular basis. It can be in bucket increments, or in the rolling holding tank of a camp toilet, or in a built in holding tank that requires moving the tiny home to a dump station.  However, the use of a built in holding tank can allow for a semi-permanent connection to a sewer or septic tank, so long as you ensure a proper slope to the connection and make sure it can withstand the weather. The most convenient solution of course is to hook up to a septic system or a sewer system. However, this is a more permanent style of connection, (unless you hook up with a flexible RV style sewer hose) and limits the mobility of your tiny house. With a septic/sewer hook up, you are also able to use any style of household toilet that you like from a hardware/home improvement store. There are other toilet options available, such as incinerating toilets and many varieties of composting toilets all with different configurations, but the most common solutions are introduced above.

Winterization concerns

No, not this sort!
No, not this sort!

Unless you plan on building your tiny house in the tropics, say, underneath a palm tree overlooking a crystal clear lagoon, with the breakers softly shushing over the reef, while you snooze away in your hammock.. um, where was I? Oh yeah, UNLESS you build in a warm climate, you will probably want to consider ways to keep your pipes from freezing. Just like in a larger house, care will need to be taken to protect your water pipes lest you wake up one frigid morning unable to make your morning cuppa coffee. Unlike RVs and campers, which are typically used only during warm weather, most tiny houses are expected to be used year round. Like RVs and campers, it is harder to protect the pipes in a tiny house than in a regular house, because there is less to protect the pipes.

There are three main ways to protect pipes: Running water, Heat, and Insulation.

Running Water

Running water at sink
Running water at sink

You often hear the advice that to keep pipes from freezing, you should crack open a faucet to let a small trickle of water to continuously flow through the pipes. Well, it does help, but in a hard freeze (defined as at least 2 hours of air temperatures below 26°F (-3.3°C) it guarantee results. The reason that it helps is that running water, by definition is not frozen, and by running a trickle through the pipes, when the water reaches whatever part at the highest risk of freezing. it does cool down, but it doesn’t stay in that part of the pipe long enough to cool down enough to be an issue. Plus, it is always being replaced by new water at the warmer, supply temperature. For best results, most guidance on the matter states that the water stream should be as thin as possible to keep a constant flow of water, which should be about the diameter of a pencil lead. The downfall of course, is that this wastes water, to the tune of around 90 gallons a day per faucet! But, it does work.


Another way to keep pipes from freezing is through the application of heat. This can either be externally, by keeping them running through interior, heated spaces, or by applying heat to them via a heating cable, or internally, by running hot or warm water through the pipes by having a recirculating circuit.

13 ft pipe heating cable with auto thermostat
13 ft pipe heating cable with auto thermostat

A heating cable basically is a linear resistance heater, designed to be wrapped along a pipe such that it looks similar to a candy cane. They typically have an indicator light that is lit when it is on, and the better versions have automatic thermostats so it will automatically turn on and provide protection when the temperature drops below a set point. They work down to lower temperatures than just running water through the pipes, typically providing protection down to around -50°F (-45.6°C). At an average price in the U.S. of $0.1231 a Kilowatt Hour, a 13 foot cable would only use about 3 cents a day.


The aforementioned recirculating circuit basically consists of adding a return circuit to the plumbing with a small pump that allows you to constantly run water from a tank style hot water heater through the pipes and back to the tank. It works, but there is the added cost of the additional plumbing for the return run, the cost of the pump, the cost to run the pump, and the cost to slightly reheat the semi-cool water as it is returned to the water heater tank. Because of these costs, especially when compared to the nominal cost to run heating cables, these sorts of systems are not typically used for freeze protection. They tend to be used in higher end houses to ensure that there is instant hot water available when you turn on a faucet.


Foam Pipe Insulation, 4 pack of 3 foot sections
Foam Pipe Insulation, 4 pack of 3 foot sections

The other primary means of keeping pipes from freezing is to insulate them. this used to be done via asbestos sheathing, however as friable asbestos is NOT worth the health risk in case of inhalation of the asbestos fibers, this has been outlawed. Since then, the building products industry have come with the closed cell pipe insulation, which look like mini-pool noodles, split down the side, with double sided tape already applied to one side of the split so you can seal it around the pipe after slipping it on. They work by helping to keep the heat contained in the water in the pipe from escaping.


Of course, there are a number of other ways that you can deal with water systems, but I have tried to touch on the main ones that most tiny house people will chose from. Next up, I will delve into cooling systems.