Water System Design

I'll share the electrical system design shortly - basically it's self-sufficient so shouldn't need to ever plug the van in anywhere.

So beyond electrical power, the next hardest resource to acquire on the road is fresh water. So we want plenty of it. And since the garage is built around bike (and gear) storage, after a day of adventure, we're going to be ready to clean up with a shower before going to bed.

And we want to be able to use the van's water system even in freezing weather (mountains, occasional 'up north' snow shoe or skiing trip, steelhead fishing, etc.).

So here's the water plan to accomplish that.

Goals:

• Complete water system use in all 4 seasons
• Lots of fresh water, even more during 3 season use
• With multiple fresh tanks, keep control over filling, usage, and transfer (no auto-magic switching)
• Avoid water waste and always have hot water without waiting
• Fast fresh water tank filling (no gravity feed)
• Eliminate any chance of simple fitting failure inside the van from draining entire tank into the van
• “Guaranteed” safe drinking water regardless of water fill source
• Charcoal filter all water fill sources to improve odor & taste

Layout Notes

• Water cabinet and kitchen galley passenger side
• Interior shower driver side

Features:

• Large, robust 3/8” walled Trionic 31 gallon primary fresh water tank inside; blank tank; use uniseal fittings on top of tank w/ pickup tube for draw
• Northwest conversions 20 gallon driver side undermount gray tank
• SBFilters 20 gallon passenger side undermount fresh water tank
• Recirculating hot water line
• Thetford Curve toilet is completely self contained; no plumbing impact
• 3 way valve to switch from exterior gray tank to small, interior gray tank(s) that are easy to empty during winter use.
• KUS level sensors on all tanks connected to Cerbo GX for monitoring
• Add 6” inspection hatch to all tanks; use Neal Carney’s excellent design and sendcutsend for hatch rings that can pull the tank wall flat for solid seal at the hatch
• PEX-A for all lines and fittings; using poly fittings over brass.
• 1/2” PEX for almost all lines; gray drains are 3/4” PEX
• Cross van under floor channel plumbing (still interior) has 2 heat cables along it. No fittings in the floor; only at the exposed ends of the lines.
• Small pex expansion compatible shutoff ball valves on every fixture supply line; can isolate a leak and continue to use rest of system.
• Use leftover 1/2” minicell on all 4 sides of interior fresh water tank; aim to reduce condensation sweat in some environments (thanks MsNomer!)
• No accumulator; unnecessary with Shurflo pump and past experience shows zero benefit; simply takes up space and adds freeze draining complexity

Tank Filling Plan

• Use Aquor RV inlet quick connect - pressurized source. Use 1/2” NPT for fill inlet on tanks. Use larger than 1/2” NPT for fresh water tank vent + overfill relief to avoid any possibility of tank damage.
• Carry water bandit to pressure fill from faucets without threads
• Carry simple 12V inline pump to create a pressure fill hose if needed from random water container
• Use high flow charcoal filter to improve smell & taste without impacting fill rate
• Use 3 way valve to select target tank for filling
• Use 3 way valve to select source tank for fresh water draw by pump
• Use an adjustable water regulator w/ gauge during filling to keep an eye on pressure, esp. from unknown sources.

Tank Transfer Plan

• Use 3 way valve right after the pump to redirect pressurized water back to the low pressure fill line. Pump will activate and based on 3 way filling valve position, pump water from one tank to the other. Can move primary to secondary or vice versa without adding another pump.
• Can move water lower in the van for weight (primary to secondary) or the other way if the weather forecast looks bad (secondary to primary).

Recirculating Plan

• Interior shower and rear shower have hot water return lines that will tee together, go through a motorized 1/2” NPT ball shutoff valve, and tee into the fill line. To recirculate, just open the valve for 20-30 seconds. It will trigger the demand pump to activate until valve is closed again.
• By connecting to fill line, lets me recirculate warmer water through either fresh water tank. I could recirculate 4 gallons of hot water into a tank to raise the overall temp in the tank if freezing weather was coming. Way easier than trying to add tank heater.
• Kitchen hot doesn't need return line; feed is very short; could always add later if needed

Alternate Interior Winter Gray Tank Plan

• Connect portable-ish scepter water tanks in the garage with some flexible hose fitting to a 1/2” gray PEX line
• Flip the 3 way valve to direct gray sump area to the lift pump and close off line to undermount tank
• When using water at kitchen sink or shower, manually run the ‘lift pump’ as needed to get the gray water up and back into the scepter tank
• ‘Lift pump’ is just a Shurflow 4008 demand pump w/ a strainer (same as our old Scamp 13 trailer had which seemed to work fine); pump can run dry and self-priming
• Scepter tanks can be removed fairly easily for dumping when all normal campground dump stations are long past winterized and closed

Drain Plan

• Motorized 1” full port ball valves on gray tank and passenger undermount tank for draining
• Interior tank can be drained just by running the pump (at 4 gpm it is less than 8 minutes when completely full). Do not want to risk adding a drain fitting low on the tank.
• Can drain 4 gallon Bosch water heater by disconnecting the cold supply line and slipping in the feed tube to a simple 12V pump.
• If long term winter storage is needed, can blow out the water lines using a compressor (I can control the output pressure of the compressor to be pretty low to avoid line + fitting damage).

Tank Venting Plan

• Use Hepvo P traps at kitchen sink and interior shower drain. Specs claim it works as a vent in addition to a trap.
• Use large 3/4” NPT vents on both fresh water tanks to avoid pressure buildup during fill.
• Route interior fresh tank vent w/ high loop and back through floor fitting. Prevents any “slosh spill” while driving with full tank. Also works great with pressure fill (can just connect, turn on high, walk away, and come back to water exiting the bottom of the van without any chance of dripping or spills into the back)
• Be mindful of air lock potential on drain lines

Rear Outdoor Shower Plan

• Use another Aquor RV inlet quick connect with shower/spray fixture hose attached. Fast and simple to connect; multiple head options. Less cabinet space impact vs. retractable hose things.
• Independent tiny mixing valve preserves cabinet space while gaining fixture flexibility

Fresh Water Safety

All fresh water headed for the tanks passes through a Blu Tech 3 stage water filtration system first. Goes down to 0.2 micron, but still reasonable flow supposedly. Time will tell. This makes shower and cleaning dishes even safe.

Further, the clean fresh water can take on a tank smell/taste after awhile no matter what you do. So we're adding a small drinking water faucet at the kitchen sink. Water headed to that goes through both a carbon filter to eliminate any tank taste and gets a final safety dose of UV disinfection with the tiny Aquisense PearlAqua Micro.

We could actually in a pinch just take reasonably clean water from a creek or river and pump that into the tanks through the filtration system and be perfectly safe.

Consider Ready-to-Go Winter Mode?

Ideal if one could leave some water in the fresh water interior tank so that using the van for a quick unplanned trip in the winter is fast. During module build out, think about closing off the water cabinet + kitchen sink area internally so that this smaller space could be electrically heated while rest of van is unheated on the driveway. Maybe flexibly plumb the pump so that it can be quickly isolated and drained (most vulnerable part). Hepvo traps don’t need any draining.

Open Items

1. Gray water “sump” available area is vertically challenged. It’s under the shower and will probably be some sort of custom fabricobbled box w/ 3/4” NPT inlet, 1/2” NPT lift pump draw, and 3/4” NPT outlet to undermount gray tank. Overall height maybe 3” max. More of a simple collection box vs. a true lowest point sump. Hepvo on the shower drain will avoid any backflow up into shower base (next lowest point). Must make it somewhat accessible for maintenance if required. Thoughts? Whale Gulper stuff doesn’t fit - too tall - and don’t need the automatic level pump trigger complexity.
2. The 3 way valve for which fresh tank the pump draws from probably needs to be motorized. I’ll want to control that while filling at the rear doors, but also from inside during use. The valve will sit in either position for long periods of time so it can’t be an auto-return to position valve which requires power for the ‘other’ position.  This valve should work for that, but pricey. US Solid doesn’t offer a 3 way for potable water without auto-return (not that I can find).
3. Check valves?
4. Vacuum breakers?