Water Before the Well: Hauling, Tanks and Catchment

Everyone arrives planning to drill a well. Almost nobody drills one in the first year.

The reason is arithmetic. Median depth for a domestic well drilled in the Sunsites and Pearce area since 2015 is 540 feet, and depth is what drives drilling cost. Meanwhile you need water on the parcel to do anything at all — to mix anything, to wash anything, to keep a person working through a June afternoon.

So the realistic sequence for most parcels here is: hauled water and a tank now, a well later, and the tank stays afterwards as backup. That is not a compromise. Keeping the tank is what you want anyway the first time a pump fails in July.

How much water you actually use

Off-grid consumption is a long way below a city household, because everything about the setup pushes it down.

Add to that anything you do on the parcel: dust control, mixing concrete, washing equipment. Construction phases use far more water than living does.

Sizing the tank

Two constraints set the size, and they pull in the same direction.

Your reserve. You want at least two weeks of usage in the tank at all times, and a month is better. That reserve is what makes a delayed delivery an inconvenience instead of a crisis.

The hauler's minimum load. Haulers usually have a minimum delivery, which means a tank smaller than that minimum wastes a trip. There is also a per-trip cost baked into any delivery, so more gallons per trip is cheaper per gallon. A tank that can take a full load in one fill is meaningfully cheaper to run than one that cannot.

Practical result: 2,500 gallons is a sensible floor for a single occupant and 5,000 for a family. Going larger is usually cheap per gallon and almost always worth it.

The pad, which is the part people get wrong

This is our end of the job and it is where the failures happen.

Water weighs about 8.34 pounds per gallon. A full 2,500 gallon tank is a little over ten tons. A 5,000 gallon tank is over twenty. That load sits on a footprint of maybe a hundred square feet, and it goes on and off repeatedly as the tank fills and empties.

What that requires:

• Continuous, level, compacted support under the entire base. Not blocks, not railway sleepers, not a couple of high spots. Poly tanks are designed to be supported uniformly; point loading a plastic tank with twenty tons in it is how a tank splits.
• Level, genuinely. An out-of-level tank loads one side of the wall and stresses the fittings. It also gives you a false level reading.
• Compaction, properly. Uncompacted fill under a cycling twenty-ton load settles, and settlement is differential — one side goes down more than the other. Now the tank is out of level and the outlet plumbing is in tension.
• Sand or fine base as a bedding layer, free of sharp rock. A stone under a poly tank is a stress concentration.
• Drainage away from the pad. Water pooling around the base undermines it, and a tank pad is exactly the sort of flat spot that collects runoff if you do not grade around it.

Horizontal leg tanks have their own requirement: they must sit on a continuously supported flat surface, not on blocks under the ends. It is a common mistake and an expensive one.

Getting pressure

Two routes, and they are not exclusive.

Gravity

Elevation is free pressure and it never fails. Roughly 2.31 feet of elevation gives you 1 PSI. So:

• 10 feet of rise ≈ 4.3 PSI — enough for a gravity-fed hose, not enough for a shower.
• 30 feet ≈ 13 PSI — usable for undemanding fixtures.
• 70 feet ≈ 30 PSI — approaching normal household pressure.

On a valley-floor parcel, seventy feet of natural elevation within a sensible distance of the house is rare. Where the terrain gives it to you, take it — a system with no pump has nothing to break. Where it does not, gravity still earns its keep as a backup: even 10 PSI means you have running water when the power is off.

Pump and pressure tank

The standard setup: a 12V or 24V demand pump, a pressure tank, and household plumbing. A 3.0 GPM pump at around 55 PSI shutoff handles a normal single-family draw comfortably.

Two things worth understanding. First, a bigger pump is not automatically better — a 5.5 GPM pump draws roughly double the current, which means heavier DC wiring and a larger fuse, and on a solar system that current matters. Second, the pressure tank's rated volume is not usable water. A "20 gallon" tank on a 30/50 PSI switch delivers roughly a quarter of that between pump starts, and that drawdown is what determines how often the pump cycles. Undersizing the pressure tank is what makes a pump short-cycle itself to death.

Filtration and testing

Hauled water arrives as clean as the last tank it sat in and the hose that moved it. Treat it accordingly.

Dedicate a potable hose and keep it off the ground. This is the cheapest and most-skipped part of the whole system.

Sediment then carbon as a baseline, in that order. Fine carbon blocks are excellent and will blind off fast if you put them ahead of a sediment filter rather than behind one.

UV if you want to be confident about bacteria, with two conditions people ignore: it needs clear low-turbidity feed water to hit its rated dose, and it needs an annual lamp replacement. A UV lamp still glowing after three years is not still working.

Test. Coliform on a schedule and after any disruption. And if you go to a well later, test for arsenic specifically — it occurs in Arizona groundwater, it is odourless and tasteless, and the general-purpose strip panels do not detect it.

What the monsoon can actually contribute

Arizona is unusually friendly to rainwater harvesting and the state encourages it. The arithmetic is genuinely worth doing, but do it honestly.

A roof collects roughly 0.6 gallons per square foot per inch of rain, before losses. At Pearce–Sunsites, with an annual normal of 12.19 inches:

Then the catch, which is the one that decides whether this is worth building: 57 percent of that arrives in July, August and September. Your collection is concentrated into a quarter of the year, so the constraint is not roof area, it is storage. Without enough tank capacity to hold the monsoon surplus through to the following June, most of what you collect overflows.

Which is why rainwater here works best as a supplement that reduces hauling frequency, and as a genuinely useful source for anything that does not need to be potable — dust control, mixing, livestock, landscape establishment. Chasing full potable independence from a valley-floor roof in a twelve-inch-a-year climate means a very large amount of storage.

A basic system is gutters, a first-flush diverter to dump the dirty initial runoff, and storage. For potable use, add filtration and UV.

How to build it so it is not wasted later

The point of doing this properly is that none of it becomes redundant when the well goes in.

1. Site the tank where it stays. Uphill of the house if the ground offers it, and clear of the future septic field and the future well location.
2. Build a pad for the tank you will eventually want, not the one you can afford this month. Extending a compacted pad later is a mobilisation.
3. Trench the supply line to the house properly, once. Below any risk of surface damage, sloped so it can drain, and with a spare conduit alongside it while the trench is open. Opening the same trench twice is the expensive way to do this.
4. Put a float valve on the inlet so a delivery cannot overfill it.
5. Fit a level gauge. Guessing whether you can make it to the next delivery gets old immediately.
6. Plumb so the well can be added later without redoing the house side. When the well goes in, it feeds the same tank, and you keep the storage and the pressure system you already built.

Done in that order, the hauled-water setup is not a stopgap you throw away — it is stage one of the permanent system, and the well is stage two.

Tank pads, trenching and the earthwork around all of this is what we do. If you are working out where the tank goes and how big the pad needs to be, that is worth getting right the first time.