Paul Industries is a nationwide process-equipment and sanitary-piping contractor working across Arizona: purified water systems, sanitary process piping, cleanrooms, CIP and process equipment installation. Arizona imposes a constraint most states do not. A high-purity water system does not only consume water, it rejects a substantial fraction of what it takes in, and in a water-constrained state that reject stream stops being a drain question and becomes a design driver.
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Arizona groundwater permitting, and why the route matters
Arizona regulates water access in a way few other states do, and the route a facility takes has long-term consequences. Within Active Management Areas the Assured Water Supply framework governs new development, but a general industrial use permit under Arizona Revised Statutes section 45-515 can allow an industrial facility to self-supply groundwater outside a city service area. A general industrial use means a non-irrigation use, excluding dewatering, mineral extraction and metallurgical processing, and excluding uses for which a certificate of assured water supply is required.
For a process plant that is not an administrative detail, it is a design input. A site self-supplying groundwater owns its own feed water quality, which determines pretreatment scope, achievable reverse osmosis recovery and how much water leaves as concentrate rather than product. A site on municipal supply inherits whatever the utility delivers, including seasonal variation it does not control.
The practical advice is to settle the water route before the purified water system is specified rather than after. The feed analysis that determines your pretreatment train depends entirely on which source you are on, and a system designed for one and connected to the other will either underperform or carry capacity it never needed.
Where the rejected water can actually go
Reject is not waste until you decide it is. These are the realistic destinations, and the chemistry check each one needs.
| Destination | Works when | Check first |
|---|---|---|
| Cooling tower makeup | Usually the best single option; towers concentrate water anyway | Silica and hardness, which can trade a water problem for a scaling one |
| Second-stage RO | Feed chemistry allows further concentration without scaling | Scaling indices at the higher concentration factor |
| Washdown and non-critical cleaning | The duty tolerates elevated dissolved solids | Whether any food or product contact occurs |
| Irrigation or landscape | Site has the land and the permit | Sodium and chloride loading on soil |
| Boiler makeup | Rarely; concentrate is usually the wrong direction | Generally not suitable without further treatment |
| Drain | Default, and the one worth designing away from | Discharge permit limits and volume-based charges |
The single most useful move on most Arizona sites is routing concentrate to cooling tower makeup, because the tower is usually the largest water consumer on site and it tolerates worse water than the process does. The check that matters is silica: concentrate that scales a membrane will also scale a tower, and solving it there is not obviously easier.
Purified water systems reject more water than most budgets assume
Reverse osmosis works by pushing feed water against a membrane and producing two streams: permeate, which is your product, and concentrate, which carries the rejected dissolved solids away. Recovery varies with feed quality, temperature, staging and how hard the system is pushed, but a meaningful share of the feed always leaves as concentrate rather than as usable water.
In most states that concentrate goes to drain and nobody thinks about it again. In Arizona it is worth thinking about twice: once because the water itself is a constrained resource with a cost, and again because discharge of a concentrated stream carries its own permit considerations. The engineering responses are ordinary but need designing in rather than retrofitting. Higher-recovery staging where the feed chemistry allows it. Routing concentrate to duties that can tolerate it, most obviously cooling tower makeup, rather than sending clean-ish water to drain. Softening or antiscalant strategies that allow the system to run at higher recovery without fouling.
The related point is that cooling towers frequently consume more water than the process does, through evaporation and blowdown. On a site where total water use is the constrained number, optimizing the purified water system while ignoring the cooling tower solves the smaller half of the problem.
Three sectors, three different water specifications
| Sector | Water requirement | Where the volume goes |
|---|---|---|
| Pharmaceutical | USP Purified Water, or WFI at 0.25 EU/mL for parenterals | Process use plus loop sanitization |
| Medical device | Purified Water or DI specified by resistivity | Ultrasonic cleaning and final rinse |
| Semiconductor | Ultrapure water to resistivity rather than a compendial monograph | Very high volume rinsing |
| Food and beverage | Treated process water | Product, cleaning and washdown |
| All of the above | Cooling water | Evaporation and blowdown, often the largest single use |
Semiconductor ultrapure water is specified to resistivity rather than to a USP monograph and is a different discipline from pharmaceutical water. Our work is the pharmaceutical, device and food side; we mention the distinction because in Arizona the two get conflated more often than anywhere else, and a contractor who does not draw the line clearly is a contractor to be careful with.
What we build for Arizona facilities
- Purified water systems Generation, storage and distribution designed with recovery and reject routing considered, not treated as an afterthought.
- Pretreatment and filtration The stages that determine how hard the membranes can be pushed and how much water is recovered.
- Sanitary process piping Drainable, cleanable stainless to the standard the product regime requires.
- Cleanrooms ISO 14644 classified environments for device and pharmaceutical production.
- Cooling and utilities Where most of a site’s water actually goes, and where reject water can often be usefully redirected.
Because reject water is the constrained resource here, wash-down design matters as much as the water train itself: CIP/SIP systems sized for recovery rather than for drain, and passivation of the recovery loop so the recycled stream does not carry iron back into the process.
Why Paul Industries in Arizona
Because a water system designed only against its product specification will meet that specification and consume more water than it needed to. Looking at recovery, reject routing and cooling makeup together is the difference between a compliant system and an efficient one, and in Arizona that difference has a cost attached every month for the life of the plant.
Standards referenced: EIA electricity price data · ASME BPE · ISO 14644-1
Frequently asked questions
How much water does a purified water system actually reject?
It depends on feed quality, temperature, staging and how hard the system is run, but a meaningful fraction of the feed always leaves as concentrate rather than as product. Softer, warmer feed water and multi-stage arrangements allow higher recovery; hard or high-silica feed limits it, because pushing recovery too far scales the membranes. The honest answer for any specific site comes from the feed water analysis, not from a rule of thumb.
Can RO reject water be reused?
Frequently yes, for duties that tolerate elevated dissolved solids. Cooling tower makeup is the usual destination, since the tower concentrates water anyway and reject is still far better quality than many alternatives. Irrigation and non-critical washing are others. What matters is checking the chemistry against the receiving duty, because sending high-silica or high-hardness concentrate to a tower can trade a water problem for a scaling problem.
Where does most of our site water actually go?
On many sites, the cooling tower rather than the process. Towers lose water continuously to evaporation and must be blown down to control the concentration of dissolved solids, and those two together frequently exceed process water use. If total site water is the constrained number, the tower is usually where the largest reduction is available, which is why we look at the utilities alongside the purified water system.
Can we run RO at higher recovery to save water?
Sometimes, and it is worth analyzing. Higher recovery means concentrating the rejected solids further, which increases scaling and fouling risk, so it depends on feed chemistry and on the pretreatment in front of the membranes. Softening, antiscalant dosing and staging all extend how far you can push it. What you cannot do is simply turn recovery up on an existing system and expect the membranes to tolerate it.
Is semiconductor ultrapure water the same as pharmaceutical water?
No, and conflating them causes real problems. Semiconductor ultrapure water is specified to resistivity and particle and organic limits aimed at not damaging a wafer. Pharmaceutical water is specified to a compendial monograph with conductivity, total organic carbon and, for WFI, endotoxin limits aimed at patient safety. They demand different validation and different expertise. Our work is the pharmaceutical, device and food side.
Does water scarcity change how we should size a system?
It changes what oversizing costs you. An oversized purified water system in a water-rich state wastes some capital. In Arizona it also wastes water continuously, because a system running well below its design point often recovers less efficiently and sanitizes a larger volume than necessary. Sizing against genuine peak demand rather than a comfortable margin is worth more here than elsewhere.
What water does a medical device line need?
Usually USP Purified Water or deionized water specified by resistivity rather than WFI, because device cleaning validation targets removal of manufacturing residues rather than control of a parenteral endotoxin limit. That matters for water consumption too, since a Purified Water system is simpler and typically less wasteful than a WFI system with a hot circulating loop and frequent sanitization.
Do sanitization cycles use a lot of water?
More than people expect, and it is recurring rather than one-off. Each sanitization involves flushing, the cycle itself and rinsing to return the system to specification, and the volume scales with loop size. That is another reason loop design matters in a constrained state: a loop that can be sanitized in sections uses less water per event than one that must be treated as a single indivisible system.
Does Arizona energy cost affect design?
Less than water does. Industrial electricity averaged 7.90 cents per kilowatt-hour in 2024 against a national average of 8.13 (EIA), so just below the midpoint and not a major design driver. The relevant interaction is that water-saving measures sometimes cost energy, for example additional pumping for reject recovery, and in Arizona that trade generally favors saving the water.
How do I get a quote for an Arizona project?
Use the form on this page or call 201-450-8280. The most useful input here is a feed water analysis, because it determines achievable recovery and therefore how much water the system will consume for the life of the plant. Beyond that: the product and its regulatory regime, your peak demand rather than average, and what your cooling towers currently use.
What recovery rate is realistic for a reverse osmosis system?
It depends on feed chemistry, principally the scaling potential from calcium, silica and sulphates, and on whether antiscalant and pH adjustment are used. Pushing recovery beyond what the chemistry supports produces scaling, cleaning frequency and membrane replacement rather than water savings.
What is the concentrate stream and where can it go?
It is the rejected water carrying the concentrated dissolved solids. Disposal options include sewer discharge subject to the local limits, evaporation ponds, reuse in cooling or irrigation where quality permits, or further treatment. In a water-constrained state the disposal route often decides the recovery target.
Can reverse osmosis reject water be reused in a regulated facility?
For non-product uses such as cooling tower makeup, irrigation or washdown, frequently yes, subject to its quality. It cannot re-enter a compendial water train. The reuse has to be designed in, because retrofitting a second distribution is expensive.
How much water does a cooling tower use compared with a purified water system?
On most sites the cooling tower consumes far more, through evaporation and blowdown, than the purified water system rejects. Water conservation efforts aimed only at the purified water system usually target the smaller number.
What is a Designated Groundwater Basin and why does it matter?
Arizona manages groundwater through designated management areas with their own withdrawal rules and permitting. Whether a site draws groundwater, municipal supply or effluent changes both the permitting route and the reliability assumption behind the design.
What pretreatment does high-hardness Arizona feed water need?
Typically softening or antiscalant dosing with pH control ahead of the membranes, sized from the actual hardness and silica in the supply. Without it, recovery has to be dropped to avoid scaling, which raises reject volume in a state where that matters.
How is a water balance built for an Arizona site?
By metering or estimating each major consumer, meaning cooling, washdown, process, sanitary and irrigation, and reconciling against the incoming meter. Most sites find the answer is not where they assumed, which is why conservation projects target the wrong system.
How much water do sanitisation cycles consume?
Hot water sanitisation and steam sanitisation both consume and discharge substantial volumes, and frequent sanitisation on an ambient system adds up over a year. Where water is scarce, ozone-based control reduces the water cost of microbial control considerably.
Does Arizona heat affect equipment selection?
Yes, particularly for air-cooled equipment whose capacity falls as ambient temperature rises, so chillers and compressors are selected against the design summer condition rather than nominal ratings. Equipment sized on nominal capacity fails in July.
Can evaporative cooling be used in a water-constrained state?
It is very effective in dry heat and it consumes water, which is the trade. Many Arizona sites use hybrid systems that run dry when ambient allows and wet only at peak, which captures most of the efficiency for a fraction of the water.
Does water scarcity change how a purified water system should be sized?
It argues for sizing closer to actual demand rather than adding generous margin, because oversized systems reject proportionally more water at low utilisation. It also argues for storage that lets the generation run at its efficient point.
What should an Arizona site examine first to reduce water use?
A site water balance showing where the water actually goes, which on most plants is cooling and washdown rather than process. Optimisation without that balance usually targets the visible system rather than the large one.
How does high total dissolved solids feed water change the design?
It lowers achievable recovery, raises antiscalant and cleaning demand, and can make a two-pass arrangement necessary. It also raises the concentrate strength, which makes disposal harder. Feed analysis is the cheapest input to the whole design.
Do Arizona data centre and semiconductor expansions affect contractor availability?
Large construction programmes absorb skilled mechanical trades, so crew availability can set the schedule on smaller process projects. Confirming crew commitment at award rather than at mobilisation is the practical response.
What is the payback on water recovery in Arizona?
It depends on the local water and sewer tariff and on whether discharge is constrained, and in some jurisdictions the binding constraint is an allocation rather than a price. Where the constraint is allocation, recovery buys capacity rather than savings.
Planning an Arizona project where water use matters?
Send us a feed water analysis and we will tell you what recovery is realistic. Call 201-450-8280 or use the form below.
