Pure Water Occasional. April, 2025
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In this Springtime Occasional you'll hear about ppm, ppb and the measuring of tiny water constituents, disputes about water treaties, heavy water pollution in England, a state ban on public water fluoridation, the world's most beautiful sewage treatment plant, the most popular water treatment chemicals, Big Tech's scheme to suck water from the nation's driest regions, record setting temperatures in 2024, America's most endangered rivers list, the advantages of parallel filter installation, factors that affect RO water production, and, as always, there is much, much more.
Thank you for reading, and sincere thanks from Pure Water Products for your continuing support. |
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Pure Water Annie’s FAQ Series
Pure Water Gazette Technical Wizard Pure Water Annie Answers All the Persistent Questions about Water Treatment.

Parts per Million. Parts per Billion.
The constituents that are dissolved or suspended in water, whether
they are natural minerals or serious chemical contaminants, are usually
measured in either “parts per million” or “parts per billion.” Another
way of expressing the same values is “milligrams per liter” or
“micrograms per liter.”
There are a variety of ways to express these same values.
mg/L or ug/L
ppm or ppb
are the same.
The u is sometimes written as the Greek letter µ, but the meaning is the same.
When you read a water test, the first thing
you need to notice is what the unit of measurement is. Is the
contaminant being reported as parts per million or parts per billion?
To say the least, this is important, because one part per million
represents a quantity one thousand times greater than one part per
billion. I won’t bother with the old “if you cut a pie into a million
pieces” explanation.
To convert parts per billion to parts per million, divide by 1,000.
If the EPA’s maximum allowable (MCL) for an industrial chemical is 2
ppb, dividing 2 by 1,000 gives you the allowable in ppm: 0.002.
If a water test reports in mg/L, you get the ug/L by multiplying by
1,000. If a test finds 0.015 parts per million of a substance, it’s the
equivalent of 15 parts per billion.
Parts per trillion, by the way, is usually expressed as ng/L (nanograms per liter) and 1 ug/L = 1000 ng/L.
It is hard to think through the relationships between water
contaminants because they vary so greatly and are seldom expressed in
the same denomination. For example:
The current “allowable” (MCL) for nitrates (which many cities in Iowa
are finding hard to meet) is 10 parts per million. That’s 10,000
parts per billion, or 10,000,000 parts per trillion.
The current allowable for arsenic is 0.010 parts per million. That’s 10 parts per billion or 10,000 parts per trillion.
The current allowable for lead is 0.015 parts per million. That’s 15 parts per billion or 15,000 parts per trillion.
There is no national allowable for the likely carcinogen 1,2,3
-Triclopropane (TCP), but California’s proposed limit is 5 parts per
trillion. That’s 0.005 parts per billion or 0.000005 parts per million.
One other measurement that is often encountered in water treatment,
especially when water softeners are involved, is the “grain.” A grain is
the equivalent of about 17.1 parts per million. Water hardness is most
often expressed in grains. If a water test reports hardness as 200 ppm,
you can convert to grains per gallon by dividing the 200 by 17. In
round numbers, 100 ppm equals about 6 grains.
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The Viqua VH200 Series UV Units
The Perfect UV Unit for Most Residential Applications
The Viqua VH200 F10
The compact but powerful Viqua VH200 ultraviolet unit is ideal for most residential use, either for well water or city water. Though it is rated for nine gallons per minute service flow, the unit puts out double the dosage needed for bacteria like E. coli even at sixteen gallons per minute. This makes it plenty powerful for all but very large homes.
The VH200 is an economical unit that uses only about half as much current as a 60-watt light bulb and consequently it generates far less unwanted heat than more powerful UV units.
The VH200 comes from the factory in two formats: as a single, independent UV chamber, or as a bracket-mounted 2-stage system that includes a 4″ X 10″ sediment filter. (See picture above.) In either format it can easily be coupled with standard filtration equipment to add carbon filtration as well.
Viqua VH200 UV Unit comes complete with mounting clips. Easy to install, easy to maintain.
Here are some highlights:
- Versatile: Available with a sediment prefilter (Model VH200 F-10), and can be easily combined with other standard filtration equipment if desired.
- Convenient: Mounted on a reversible, heavy duty, painted steel bracket for installation flexibility and convenience. This means you can install with the inlet water on the left or on the right. Combo inlet fits both 3/4″ and 1″ pipe.
- Ease of Maintenance: Audible lamp replacement reminder and countdown timer with digital display. It reminds you when it’s time to change the lamp. Lamp life is a bit over a year. Controller will also go into alarm if the lamp fails.
- Reliable: The constant current feature ensures stable UV lamp output, regardless of power fluctuations.
- Powerful: High-performance UV lamp, rigorously tested to provide consistent output over the entire lamp life (9000 hours). See power ratings below.
- Space Efficient: High UV output lamp technology allows for a smaller footprint, while maintaining the same UV dose as a longer chamber.
Features & Specs VH200
Disinfection Flow Rates |
16mJ/cm2 |
16 GPM (60 lpm) (3.6 m3/hr) |
30mJ/cm2 |
9 GPM (34 lpm) (2.0 m3/hr) |
40mJ/cm2 |
7 GPM (26 lpm) (1.6 m3/hr) |
Specifications |
Dimensions |
17″ x 10 1/2″ x 18″ for VH200 F10. VH200 is 17.75″ X 3.5″. |
Shipping Weight lbs (kg) |
26 lbs. for VH200 F10. (VH200 is 12 lbs.) |
Connection Size |
1″MNPT INLET / 1″ x 3/4″ COMBO OUTLET. |
Power Consumption |
35W |
Pure Water Products part numbers for these units are UV909 for VH200 single unit and UV918 for VH200 F-1 unit with sediment filter.
We also have upgrade kits that allow the VH200 to be combined with high flow carbon block systems.
UV909 Viqua VH200. UV Only. Single unit without filters.
UV918 Viqua VH200-F10. UV unit with 10″ X 4.5″ sediment filter.
UV909Plus. Pure Water Products Hybrid VH200 with sediment and carbon block filters. Consists of 4.5″ X 10″ sediment filter, 4.5″ X 20″ carbon block filter, and VH200 UV unit. Made with Pentair “Big Blue” housings. Stainless connector and pipe nipples included. (This product is not on our website. Please call for more information.)
940 382 3814
pwp@purewaterproducts.com
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Water News for April 2025

Water News for April 2025
Tensions over Kashmir and a warming planet have placed the 1960 Indus Waters Treaty on life support
Today, more than 300 million people rely on the Indus River Basin for their survival.
This has put increased pressure on the precious source of water that sits between India and Pakistan. The effects of global warming, and the continued fighting over the disputed region of Kashmir, has only added to those tensions. Excellent analysis in The Conversation
US/Mexico Water Treaty at a Standoff
Drought is preventing both the US and Mexico from fulfilling obligations of the 1944 Colorado River water treaty. 65% of Mexico is under drought conditions and the northern states are being hit hardest.
The struggles of farmers come as Mexico and the U.S. are in tense negotiations over Mexican delays in delivering the quantities of water laid out in a 1944 treaty.
President Donald Trump has threatened tariffs and sanctions if Mexico does not increase water deliveries which U.S. officials say have devastated Texan farmers. The Mexican government says drought has ravaged its ability to comply.
In the agricultural town of Julimes in Chihuahua, farmers are wondering how much longer they can survive.
“I don’t think we’ll be able to hold out much longer,” said cattle farmer Leopoldo Ochoa, 62, as he rode with his granddaughter on horseback behind his herd. Reuters.
Shocking Amounts of Raw Sewage Are Being Released into England’s Waterways

In a new report released in April, the UK’s Environment Agency (EA) revealed a staggering figure: water companies released raw sewage into England’s waterways for 3.61 million hours in 2024. While some spilling is legal, scientists are raising alarms about the potential danger to the public.
“These figures are disgraceful and are a stark reminder of how years of underinvestment have led to water companies discharging unacceptable levels of sewage into our rivers, lakes, and seas,” said Environment Secretary Steve Reed, per BBC News.
Due to the UK’s combined sewer system, both rainwater and wastewater are carried in the same pipes. Wastewater is usually treated at a sewage treatment works, but during heavy rainfall, the sewage works are at risk of being inundated. To prevent backups to the system, which could allow sewage into homes and streets, the excess flow goes straight into waterways. Water Online.
Utah Bans Fluoridation of Water
Utah has become the first US state to ban the decades-old practice of adding fluoride to public water supplies, due in part to a mix of health concerns about the practice. Utah Gov. Spencer Cox signed the new law, prohibiting fluoridation starting May 7. The move comes amid growing scrutiny of the practice, which started in the 1940s as a strategy to help people prevent cavities and reduce tooth decay.
Though more than 70% of the US population receives fluoridated public water supplies and many medical professionals support the practice, opposition has been growing due to studies suggesting fluoride may have neurotoxic effects on fetuses and young children. New Lede
Florida is also considering banning the fluoridation of water supplies.
Corrosion Inhibitors Category Dominates the Water Treatment Chemicals Market.
The Global Water Treatment Chemicals Market was valued at USD 36,815 million in 2024 and continued strong growth is expected.
Based on the type, the global water treatment chemicals market is segmented into organic coagulant, inorganic coagulant, flocculant, corrosion inhibitors, scale inhibitors, biocide & disinfectants, chelating agents, anti-foaming agents, PH adjusters & stabilizers, and others. Corrosion inhibitors have seen tremendous growth and development over the past few years due to their usefulness in industrial water systems such as cooling towers, boilers, and pipelines. This is primarily because these inhibitors prevent failure of expensive equipment and infrastructure through rust and corrosion, which eventually leads to very high maintenance costs. In addition, stricter environmental regulations coupled with continuous emphasis on sustainability push industries to invest in efficient corrosion control solutions, driving demand in the market even further. UnivDatos.
The World’s Most Beautiful Sewage Treatment Plant
A stunning new sewage treatment plant in Arklow in Ireland has been described as the most beautiful in the world. Full story with pictures in The Guardian.
Big Tech’s Plans To Suck Water from the Nation’s Driest Regions
Amazon, Microsoft and Google are operating datacentres that use vast amounts of water in some of the world’s driest areas and are building many more.
With Donald Trump pledging to support them, the three technology giants are planning hundreds of datacentres in the US and across the globe, with a potentially huge impact on populations already living with water scarcity.
“The question of water is going to become crucial,” said Lorena Jaume-Palasí, founder of the Ethical Tech Society. “Resilience from a resource perspective is going to be very difficult for those communities.”
Efforts by Amazon, the world’s largest online retailer, to mitigate its water use have sparked opposition from inside the company with one of its own sustainability experts warning that its plans are “not ethical."
In response to questions from SourceMaterial and the Guardian, spokespeople for Amazon and Google defended their developments, saying they always take water scarcity into account. Microsoft declined to provide a comment.
2024 Was A Record-Setting Year
The devastating impacts of the climate crisis reached new heights in 2024, with scores of unprecedented heatwaves, floods and storms across the globe, according to the UN’s World Meteorological Organization. The WMO’s report on 2024, the hottest year on record, sets out a trail of destruction from extreme weather. The Guardian
The Mississippi Tops the List of America’s Most Endangered Rivers
The Mississippi River ranks as the nation’s most endangered river as federal plans to cut flood relief programs meet with a rise in severe weather, a new report warns.
American Rivers, a nonprofit environmental advocacy organization, said the threats to the Mississippi River – which provides water for nearly 20 million people – come as communities along the lower river flooded from torrential rain in early April, and as Trump administration officials consider eliminating the Federal Emergency Management Agency (FEMA), which helps state and local governments respond to disasters. New Lede.
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Basic Heavy Duty Whole House Cartridge Filters

Tough, versatile 20-inch “Big Blue” housings can be used alone or in a
variety of combinations to meet virtually any “whole house” filtration
situation. They are simple, durable, easy to install, and easy to
service. They use standard-sized cartridges so replacements are easy to
find.
Parallel installation, as pictured below, make them suitable for
even large homes. Installing in parallel greatly reduces pressure loss,
enhances the effectiveness of the unit, and extends the life
expectancy of the cartridges.
Cartridge filters are much easier to maintain than tank-style
filters. As for installation, they care compact in size and do not
require electricity or connection to a drain. Most require only an
annual cartridge change, which can usually be done by the homeowner.
The chart below shows sizing suggestions for whole house filtration for water that is treated with chlorine or chloramine. Chloramine units require more expensive cartridges than than the unit
Description
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Application
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To Determine Pricing
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System 1. One 4.5″ X 20″ 5 micron sediment filter plus one 4.5″ X 20″ high performance carbon filter. |
Homes with 1 to 3 people. Flow rates to 5 gpm. |
Price is the same as WH103 on this page. |
System 2. One 4.5″ X 20″ 5 micron sediment filter plus two 4.5″ X 20″ carbon filters installed in parallel. |
Homes with up to 5 people. Flow rates to 10 gpm. |
Price is the same as one WH103 and one WH102 on this page. |
System 3. One 4.5″ X 20″ 5 micron sediment filter plus three 4.5″ X 20″ carbon filters installed in parallel. |
Homes with up to 8 people. Flow rates to 15 gpm. |
Price is the same as one WH103 and two WH102 on this page. |
Basic Housing and Bracket Setup. The Housing is available for
3 pipe sizes–3/4″, 1″, or 1.5″. This very versatile “Big Blue” housing
will accept any standard 4.5″ X 20″ cartridge. It can be used for
sediment cartridges, carbon cartridges, or “media” cartridges for
special purposes like iron removal or pH increase.
Basic Parallel Arrangement for Sediment Filter followed by two Carbon Filters installed in parallel. This arrangement increases service flow rate, extends cartridge life, and greatly increases effectiveness.
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How Temperature, Pressure, and Water Quality Affect How Much Water Your Home RO Unit Makes
If your home reverse osmosis unit is rated for 50 gallons per day
production, that means that it will, theoretically, produce water at
the rate of 50 gallons in 24 hours, or about 2 gallons per hour. What
it will actually produce is only remotely related to its advertized
production rate. It could be more, but it is often less. And it
usually doesn’t matter.
Unless you use the unit to fill an aquarium,
you probably don’t need more than a couple of gallons per day anyway. As
long that water comes out of the faucet when you request it, all is
well.
When the membrane makers give the gallons-per-day figure for their
membranes, they don’t take into account that the unit will most likely
be used on an undersink reverse osmosis unit where it has to fill a
pressurized storage tank. If the unit spends most of its time simply
topping off a pressure tank when a pint or two of water has been taken
out, its advertized production goes way down.
However, the three main variables that influence the final flow rate
of the product water from an RO unit are inlet water pressure, the TDS
(total dissolved solids) of the inlet water, and the temperature of the
inlet water. With these, the membrane maker makes certain assumptions
for residential membranes. The assumed numbers do not represent ideal
conditions or even average conditions; they are simply numbers that
have been agreed upon to provide a standard by which membrane production
performance can be measured. Here are the assumptions:
Inlet Water Pressure: 60 psi.
Inlet Water Temperature: 77 degrees F.
Inlet Water Total Dissolved Solids: 500 ppm.
The following chart shows how each of these affects the actual amount of water that comes from your unit.
Variable |
How This Affects Performance |
Discussion |
Water Temperature: 77%. |
As the temperature goes down, production goes down, sharply. As the temperature goes up, so does production. |
77 degrees F. is higher than water temperature in most areas of the
country. It, of course, varies considerably by the season, so you might
notice that your RO unit makes more water in summer than in winter. (If
your water source is a deep well, the season won’t matter much.) Note
also that as temperature and consequently production goes down, the
overall TDS rejection rate of the membrane goes up. That is, when low
temperature causes the unit to produce less water, it actually makes
better water. It isn’t practical to try to control inlet water
temperature for residential units other than by a simple fix like adding
more tubing to the inlet water line to allow exposure to ambient
temperature as the water enters the RO unit. This might speed production
up a bit in the winter.
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Inlet Pressure: 60 psi. |
As pressure goes up, production goes up; as pressure goes down, production goes down. |
60 psi is a fairly common pressure for city water, but most wells
run between 30 and 50 psi. A residential membrane makes little water at
30 psi. This variable is the easiest to control. Adding a booster pump in front of the unit will increase inlet pressure to about 80 psi and water production will go up significantly.
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TDS of Inlet Water. |
As feedwater TDS goes up, RO production goes down; as feedwater TDS goes down, production goes up. |
500 PPM TDS is higher than most city water. Typical city water
that comes from a lake, for example, might be 200 ppm. Your water is
the water your RO unit has to deal with, and there is no practical way
to alter its TDS before it enters the RO unit. (The unit will, of
course, make a 90% plus reduction in the TDS coming out.)
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How to Determine the GPD Production of Your Home RO Unit
Expected production for home reverse osmosis units is usually stated
in gallons per day (GPD). Many factors affect the production. These
include inlet water pressure, water temperature, total dissolved solids
(TDS), the condition of prefilters, etc.
Here’s an easy way to determine the actual production of your RO. The
only tools needed are a standard household measuring cup (or any
measuring device that has a milliliter, or ml, scale) and a watch or
clock with a second hand.
1. For undersink units, turn off the valve at the
top of the tank to isolate the tank from the system, then lock the
dispensing faucet open and let the unit produce into the sink for a
minute or so. The drip or small stream you see is the actual production
of the unit—how fast it is making water. (For countertop units, just
start the unit and let it produce water for four or five minutes until a
steady production rate is established.)
2. Using the watch and measuring cup, get an accurate measure of how much water the unit produces in milliliters into the cup in one minute.
3. Multiply the result by 0.38 to convert
milliliters per minute to gallons per day. The result is how many
gallons your reverse osmosis unit will produce if it runs for 24 hours.
Example: If your unit is making 50 milliliters per
minutes, multiply 50 X 0.38. The result is 19. Your unit is producing
water at the rate of 19 gallons per day. In most cases, for a residential reverse omosis unit, that's plenty.
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Places to visit for additional information:
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Pure Water Products, LLC, 523A N. Elm St., Denton, TX, 76201. www.purewaterproducts.com. Call us at 888 382 3814, or email pwp@purewaterproducts.com. |
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