Desert Water Harvester

(Published Sept. 15th, 2025; rev. 260421)

Greetings Mr. Elon Musk, I trust you are doing well. This letter is in regards to a potential means for harvesting pure drinking-water, which ideally - is powered solely by the sun. I refer to this unique system as the Desert Water Harvester since it’s desert-like conditions which make it the most practical. Basically, it’s analogous to an oasis in the midst of a desert.

I thought it only appropriate to send you this information, not only due to your obvious compassion towards humanity, but also because of your talented ways of blending differing technologies. I believe that the information herein aligns with at least a couple of your more ambitious endeavours. Hopefully, you will tend to agree.

I can assure you that there are absolutely no expectations from myself for you to reciprocate in any form or fashion, and you are perfectly free to use this information however you see fit. Further, I don’t have any products to sell, nor am I affiliated with any company nor representative who could potentially benefit from releasing this information.

In addition, this information has been forwarded to yourself due to the fact that you are both owner and director of The Boring Company. The basis of this letter, has tremendous potential for opening up a totally new-market for The Boring Company; and perhaps even others of which you are an integral part. It likely won’t take you long to realize that this project’s potential is not limited to merely earth-bound endeavours.

Desert Water Harvester -
INTRODUCTION

Although there are a few crucial pieces of information herein, for the most part - what I’m about to describe can be built upon technology which already exists. Nonetheless, there will certainly be challenges ahead to determine the correct-blend of “conventional” technologies. As well, this project has potential for developing patentable technologies which could be more exotic in fashion.

In a nutshell, this Desert Water Harvester (DWH) creates pure drinking-water directly from (potentially) contaminated-water without the use of chemicals. Energy-wise, the vast portion of its process is garnered directly from the sun’s rays.

As a first step, this unique system requires a totally-level tunnel bored to a depth that taps into the local water-table. Once the underground-water saturates the tunnel’s length... the DWH takes advantage of this reservoir's enormous surface-area for natural evaporation. A dynamic air-flow through the tunnel, is the primary-means for extracting and delivering water-vapour. Under the appropriate conditions, this water-vapour subsequently produces pure-water condensate.

The main focus of this project, hinges upon the fact that pure drinking-water can be efficiently harvested by controlling the environment of two natural processes: EVAPORATION and CONDENSATION. In so doing, the moisture extracted from the air should be totally clean regardless of probable contaminants within the original ground-water. Although typically, observing water while it evaporates and later condenses is like watching paint dry, this Desert Water Harvester will be much more dynamic.

One of the great advantages of this Desert Water Harvester, is the fact that it can be used in areas where shallow wells are no longer feasible due to contaminated ground-water. Hence, it can be used alongside farmland(s) which create harmful runoffs from chemical-fertilizers, manure, and the like.

Furthermore, since ground-water can naturally seep into a horizontal-tunnel which covers a fairly-large geographical area… spotty water-production from vertical wells may be avoided. Obviously, a ground-water assessment would have to be completed before installing a tunnel-based water-harvester, and one which is somewhat vertically-challenged (depth-wise) when compared to conventional wells.

Since this Desert Water Harvester can be installed alongside farmlands, it can be used as a source for their livestock’s drinking-water. For interest’s sake, a single-head of cattle requires approximately twenty US-gallons of water per day. Due to human activities such as showers, toilets, laundry and such; humans require at least two or three times as much potable-water than cattle. This is a ball-park estimate.

Notably, it’s easier to estimate a cattle’s daily-consumption of water than that of a human, since human water-consumption varies depending upon one’s culture and cost-of-supply. 

Setting aside a proper amount of real-estate, a Desert Water Harvester could also easily supplement a city’s water-supply. Perhaps an ideal-location for one of these systems is alongside a sprawling suburban housing-development. Theoretically, one of these water-harvesters could produce perfectly pure-water even if it was installed alongside a waste-water treatment-facility.

Energy-wise, this Desert Water Harvester will ideally be 100% powered by the sun’s rays. It’s realistic to assume that a mature DWH could deliver drinking-water at its full-capacity, even if there were a power-outage upon the local-grid. Notably, the DWH is quite efficient because it's not chemically creating H2O, but merely purifying water through a series of physical-state transitions. While so doing, its molecular contaminants remain behind. 

The following items are what I perceive to be the Desert Water Harvester's primary components. The last-two items on the list are add-ons to the basic-system.

• FIRSTLY, a completely-level bored-tunnel of sufficient length and diameter is required to extract seeping water from the local water-table. Other than nuclear-waste perhaps, the initial quality of the water is virtually insignificant. 
• SECONDLY, a large glass-building which harnesses energy from the sun, is erected directly over the tunnel. The connection between the tunnel and the building is simply a vertical-shaft. Diameter wise, this shaft’s opening is comparable to that of the tunnel.  Whereas the glass-building contains the bulk of the water-harvesting equipment and might be compared to an oversized greenhouse - its functions and features are vastly different. In addition to the sun being harnessed by photovoltaics to electrify the DWH; the sun’s rays provide energy for the evaporation-process, various air-currents, and differential temperatures.
• OPTIONALLY, a gravity-fed water-distribution system can be added to the initial DWH. This water-distribution-system utilizes a rather large water-tower in addition to pumps and instrumentation which fill and monitor the tower. If properly engineered, I believe that any undue chemicals added to the drinking-water (such as chlorine) will depend more upon the design of the water-distribution-system than the DWH itself.
• POTENTIALLY, a bio-dome could be added to the DWH for growing crops and vegetables. Due to the cooling-effect of green-plants in addition to having these same plants produce gobs of oxygen from CO2 - a thriving bio-dome benefits the water-harvester itself. Although plants absorb water from the ground, they also release moisture back into the air (transpire). Further, plants not only absorb CO2, but atmospheric-toxins as well. I wasn’t aware of this previously, but certain plants are known for absorbing VOCs like benzene and formaldehyde. Unfortunately, due to potential infestation of bugs and bacteria, the bio-dome would likely have to be segregated from most parts of the DWH. At the moment, we can only ponder the implications of such an installation.
  

At this early-stage, I’m envisioning this Desert Water Harvester project as an EXPERIMENTAL PILOT-PLANT. The flexibility of its base-system allows for easy expansion and a generous-array of options. Basically, this document outlines how I perceive to be a practical-path forward, and certainly doesn’t take into account factors of which I am likely totally ignorant of. Further, there are no right or wrong answers at this point in time, it’s just that some approaches will be more efficient and/or practical than others.

As far as this project’s topology goes, differing physical-arrangements between a potential second-tunnel and likewise further glass-buildings are perfectly acceptable.

Although each installation (site) requires a single perfectly-level tunnel, adding additional tunnels and connecting tunnels of varying depths is quite doable. In fact, I’m sure that at certain sites, having a combination of tunnels with varying-depths would likely be the preferred topology.

For visualization purposes, the following two drawings explain the gist of the system.   

Unrealized Potential of the Desert-Water-Harvester

As near as I can determine, using a totally-level tunnel combined with a huge glass-building for harvesting pure-water is quite unique. I don’t believe that we will truly understand its full potential until one is built to scale. As a crude first-approximation design-wise, there will be a certain relationship or ratio, between the surface-area of the water within the tunnel, and the surface-area of the glass-building which is exposed to the elements.

Different from many distillation-processes, the supply-water of the Desert Water Harvester is not boiled in order to change state. The DWH-process is more akin to what commonly occurs in nature. In the outdoors, surface-water evaporates off of streams, lakes, and seas; then raises towards the sun in the form of vapour. This vapor condenses and then accumulates into a cloud formation. Depending upon ambient temperature, this H2O later returns to earth in the form of either rain, hail, or snow.

Undisturbed surface-water evaporates much faster within a dry environment than one with high RH and/or saturated with moisture. Hence, the quicker that water-vapour is removed from across the surface of a body-of-water, the faster the evaporation process becomes. This is where the dynamics of the DWH gets rather interesting.

When we boil water to create steam, the whole pot of boiling water has to reach a critical temperature (100° C) before releasing its vapour as steam. In addition, it takes a certain amount of energy to not only initially create the steam, but also to ensure that the steam remains in a quite-energetic state.

In contrast to the previous scenario, the Desert Water Harvester merely focuses upon the surface-water within the tunnel while converting liquid-H2O to vapour. Assuming that the water within the tunnel is relatively still, it’s the surface-tension of the water that the air reacts with. This is where the bulk of the vapour gets created within the tunnel. It's also why the dynamics of the underground-tunnel are quite advantageous.

The intent of the tunnel, is to always have a certain amount of air-flow from one end to the other across the water’s surface. Cool-dry air absorbs moisture much easier than warm-air, which tends to have a higher relative-humidity (RH). So, as cool-air flows across the water’s surface, it naturally picks up moisture and creates additional vapour. The faster the air-velocity through the tunnel, the greater rate of vapour-production. This rapid flow-of-air, ensures that as soon as vapour gets created - it’s instantly swept away. This ensures that the RH along the surface of the water remains relatively low, and the rate of vapour-production continues to remain relatively high.

A a natural consequence of the aforementioned process, this creates evaporative-cooling within the tunnel’s ambient air. As further vapour is introduced into the air-stream, mobile water-molecules absorb a certain amount of heat-energy. In turn, this reduces the average air-temperature within the tunnel.

As a consequence of this whole process, it's many-times more efficient to create water-vapour using air-velocity through a tunnel, than it is to boil water on an open stove-stop. Nonetheless, you might well ask : “but doesn’t it take a lot of energy to move the air across the water’s surface?”

I believe that the greatest percentage of electrical-energy required for the DWH-process, will be for the blowers which have to move air from one area to the next. Here, in order to minimize electrical power-usage and optimize the system - a certain amount of experimentation will be required.

As a crucial point; within the tunnel itself it’s much more efficient to move dry-air at a certain velocity, than it is to move comparatively moist-air. Hence, we don’t want to create a high ambient RH before it’s required. A high RH (saturated air) will not be required until the air-mass reaches the dedicated-area for producing pure-water condensate. Most-likely, the condensate-collection-process will occur above ground within the glass-building. A good portion of this condensate will collect upon the glass-walls due to a contrast of temperatures, between the inside and outside of the glass building. Any remaining viable condensate, can be collected upon strategically-placed metal-plates inside the building.

By experimenting with temperatures and air-flows, I’m hoping that the energy required for blower-activities can be kept to a bare minimum. Even though the plan here, is to use solar-energy and photovoltaics as much as possible; once the system is properly-sized and tuned, then natural-convection will become more of a prominent-factor. So, the unique design of the glass-building itself, must conform to the system-wide concept of maximizing natural-convection. 

Again, the available-options here for the tunneling-system and building arrangement are quite vast. Perhaps temperature variations between one tunnel and another, could actually pull air through the glass-building. Further, by having two-glass buildings connected via a long common-tunnel, the timing of the evaporative/condensation sequence within each building could be staggered. The goal of this staggering effect, would be to create enough of a variation between atmospheric-pressures, in order to drive air-flows through the length of the tunnel. Hence, the air-flow-direction within the tunnel could periodically flip the opposite way.

Perhaps the highest-purpose for this Desert Water Harvester, is to actually install one within a desert. Depending up location, the water-table beneath a desert’s surface can be relatively-shallow or virtually unreachable. Under true desert conditions, the DWH’s tunnel would have be considerably-longer than what would otherwise be deemed normal. In addition, in order to save costs; a considerably-deep horizontal tunnel would likely have a comparatively-smaller diameter here as well.

Whereas in prior-conversations, I was considering that the tunnel would normally be half-full of water for efficiency’s-sake, beneath extreme desert-like conditions - that likely wouldn’t be the case.

Beneath a desert which experiences extremely arid conditions, a horizontal tunnel may have to be located (bored) up to one kilometer below the surface to reach water. Now, I can’t imagine boring anything that deep would be practical. Hence, installing a tunnel within an extremely-arid desert would have to be quite strategic. That being said, since a DWH’s tunnel is horizontal instead of vertical like a standard well; then the chance of striking water would be much greater at a certain depth.

It’s likely that a Desert Water Harvester installation within an extremely arid desert, might only experience water during certain months of the year. So, the methodology for its operation could be slightly different than what we’ve discussed thus far.

Nonetheless, if a cool-spring was found beneath the ground, it may still supply water throughout the year. The good news efficiency-wise here, is that whatever water is discovered deep underground will be extremely cold. Hence, the air-flow-process of the DWH that transfers water-vapour through the tunnel should be quite efficient.

Intriguingly, perhaps an air-flow injected into the horizontal-tunnel’s entrance here, would be enough retrieve an adequate supply of water-vapour at its opposing end. For this to work, there would have to be an additional vertical-shaft located at the horizontal-tunnel's exit point. If this methodology worked, then there would be no need to incorporate an underground-pump nor priming system within the vertical-shaft.

Final Thoughts

This pretty-much exhausts my thoughts regarding this Desert Water Harvester for the time being. I believe that I’ve flushed out enough ideas, so that certain experts can take it from here. My background is deep within electrical, instrumentation, and controls; not thermodynamics. I suspect that anyone with a fair-bit of thermodynamics and building-design experience, will quickly garner a gut-feel upon how to proceed.

The Lord brought this idea to my attention in January of 2023, so I’m sure it will be a resounding success. Previously, I did some work for the DWH’s water-distribution system as well. Obviously, that information is not adequately explained herein.

The water-distribution-system which I had in mind, is based upon a solar-powered gravity-feed water system. It would be quite capable of delivering water for miles in any one direction without the need of an electrical-grid. Due to the gravity-feed concept, it should be capable of supplying water 24-7.

The wild-card for this whole system concerns a potential biodome. Interestingly, plants themselves remove certain impurities like volatiles out from ambient air. I believe that the potential drawback to this biodome, is the possibility of having harmful bacteria getting mixed into the system's drinking water. This could very-well occur, if animal feces or their byproducts were used as fertilizer for green-plants which are located within the same building that produces pure-water condensate.

As I was thinking about this issue today, perhaps this biodome should be located within a separate glass-building altogether. In this scenario, the DWH's processing equipment could be installed within one building, and the biodome within another. These two glass-buildings could then be separated from one other across a certain length of tunnel. Hence, a single-tunnel could then supply water-vapour to both buildings. The drawback here of course, is that only one of these buildings could then be faithfully used as a source for pure drinking-water.

Since much of the earth's surface is contaminated to a certain extent, and many of our underground-wells have now become tainted, we need to search for viable options. The Desert Water Harvester is an efficient and viable-option for pure-water recovery, since it purifies water as it raises it out from the earth.

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