If you are going to install plumbing into your Camper build the time to plan for it is when you are building the frame of the Camper.
You can add a lot of convenience to your camper build by installing a bathroom with a toilet and a shower or you can just add the basics with running water and a sink.
If you are just going to add drinking and washing water, you will need a tank for the water, the plumbing to get water into the tank and a way to get water out of the tank usually into a sink. Then you will need a place for the water to run off too. Usually the sink runs into a grey water tank that can be emptied at a dump sight.
You will need someway to get the water out of the tank and into the sink. This can be done with a manual pump or with an electric powered pump. In most cases you will also want to add a filter to the water line ahead of the pump.
If you want hot and cold running water you will also want to add a water heater to the system. Don’t forget that the input hose for the water tank needs to have an air vent and the drain for the sink also needs to have a vent. The water heater and the water pump will also need to have power run to them.
If you want to add a bathroom with a shower you will want to run lines to the water mixer valve and to the shower head. These lines are usually run using Pex piping and can be colour coded for hot and cold water. You will also need to run cold water to the toilet.
The toilet can be of two types. The first type of toilet needs to have a water line run to it and needs to have a black water tank connected to it that can be emptied at a dump site.
The second type of toilet is a cassette toilet. The toilet still needs water run to it but it empties into a cassette tank that can be removed and emptied at a dump site. If you are going to install a Grey water tank and a black water tank in your Camper. The tanks are emptied at a dump site by connecting a hose to a gate valve and then opening the gate valve. The theory is that this system makes the process more sanitary and minimizes cleanup.
When you are installing plumbing into your Camper you can in most cases use any fixtures that you would normally use in home. There are also many Camper fixtures that are available from an RV supply house.
With the appliances and plumbing you are adding to your Camper you will want to install propane lines to all of the different appliances. You will need to plan where to run the propane lines for the Cooktop, the Furnace, the water heater and in most cases the Fridge. You can also use an induction cooktop if you have lots of power, and you can use a 12 volt only refrigerator. Don’t forget to install a Propane detector somewhere in your Camper near the floor. Propane is a heavy gas so it will tend to congregate near the floor. All of the Propane lines will go back to the Propane tank that you should mount on the outside of the Camper. The Propane tank will usually be mounted with easy access from the outside of the Camper.
Propane lines should all be run using copper lines that is rated for Propane.