Hull's tap water is a mixture of two supplies that could hardly be less alike — one lime-softened at a plant near Vermillion, South Dakota, drawing on wells beside the Missouri, one delivered with its iron and manganese stripped out and its hardness completely untouched — combined at a chemical feed building on the edge of town. Hull buys every gallon and pumps none of its own. What the mixture reads at a Hull kitchen tap is a number no agency has ever published, and that is the honest place to start.
| Hull at a glance | What the record shows |
|---|---|
| Who supplies the water | Hull Water Supply, PWSID IA8444063, serving 2,384 people across 908 service connections, classified in EPA SDWIS as purchased groundwater |
| Where it comes from | Two active purchase connections: the Rock Valley Rural Water District (IA8482701) and the Lewis & Clark Regional Water System, delivered from Vermillion, South Dakota. Every Hull-owned well is plugged or out of use |
| Softened at the plant | Partial. Hull itself softens nothing. Lewis & Clark lime-softens its half; the Rock Valley Rural Water District removes no hardness at all |
| Published hardness | None. The Iowa DNR sample database holds zero hardness results for Hull Water Supply, with the date range opened all the way back to 1900, and Hull's own 2024 water quality report prints no hardness figure either |
The federal facility inventory for Hull lists sixteen entries, and two of them are purchase connections that are both switched on: CC01 from the Rock Valley Rural Water District, and CC02 from Lewis & Clark. Neither is a standby.
You do not have to take that on inference, because the state named the evidence. Hull's active compliance sample station, facility 36607, is recorded in EPA SDWIS under the title “BLENDED RVRW / L&C @ CHEM FEED BLDG TAP”. Iowa is sampling a blend, and says so on the label. Hull's 2024 consumer confidence report says the same thing in plain English: all of the city's water is purchased, from the Rock Valley Rural Water District and from Lewis and Clark.
This is a rare arrangement, and it is worth being precise about how rare. Of Iowa's 1,078 active community water systems, 151 buy all of their water rather than pumping it — ordinary enough. By our own count of the EPA facility inventory, only four of those 151 carry two or more active purchase connections, and Hull is the only one of the four where one wholesaler softens and the other does not. Both suppliers even keep dedicated Hull hardware on their books: Lewis & Clark carries a 1.5 million gallon reservoir named for Hull, and the Rock Valley district carries a Hull booster station and an east Hull tower.
Lewis & Clark treats at Vermillion, South Dakota, drawing on the Missouri–Elk Point alluvial aquifer through eleven vertical wells and a collector well. Its plant went into service in July 2012 using traditional lime softening, and the utility publishes what comes out of it. Its 2025 water quality summary lists total hardness of 150 ppm as calcium carbonate, stated as 8.5 to 9.5 grains per gallon, alongside alkalinity of 60 ppm, calcium of 85 ppm and a pH of 8.5. That is a utility's own published figure rather than a state lab result, but it is a published figure, and at 150 mg/L it still falls in the USGS “hard” band — it is simply far softer than the other half of Hull's blend.
The Rock Valley Rural Water District is a different story, and a separate utility from the city of Rock Valley, whose supply we cover elsewhere. The district carries twenty-three federal treatment records and not one of them is a softening record. Its two plants exist to take out iron and manganese: forced-draft aeration, potassium permanganate and gravity filtration through sand and anthracite at Plant #1, forced-draft aeration and pressure filtration at Plant #2, with gaseous chlorination at both. None of that chemistry touches calcium or magnesium.
The hardness in those wells is substantial. The Iowa DNR sample database holds eight hardness results on active district wells, running from 410 mg/L at Well #8 in September 2006 to 952 mg/L at Well #20 in September 2025 — 24 to 56 grains per gallon. The shallow alluvial wells cluster tightly at 410 to 456 mg/L. The two newest wells sit far higher: 890 mg/L at Well #19 on 2 January 2024, and 952 mg/L at Well #20 on 8 September 2025. Well #20 is the only district well the Iowa DNR source water tracker logs as deep — Dakota aquifer, 505 feet; Well #19 is not in the tracker at all, so its depth is not on record.
Two honest caveats belong with those numbers. They are raw wellhead samples, not finished water. And the district blends before it delivers: its own composite sample point is named for wells 1 to 14 and 16 to 20 at the Plant 2 lab sink, so seventeen shallow wells dilute those two before anything heads toward Hull. Nobody has ever measured hardness at that composite tap. What can be said without stretching is that the district removes no hardness whatsoever, so what it delivers stays a long way above the 8.5 to 9.5 grains Lewis & Clark publishes.
We looked for one properly. The Iowa DNR drinking water portal, queried for analyte 84 — total hardness as calcium carbonate — against PWSID 8444063 with the start date set to 1900, returns no rows at all. The Iowa conveyance record for Lewis & Clark returns none either. Hull's own 2024 water quality report contains no hardness figure. The number is not buried in an archive. As far as the public record goes, it was never produced.
Even if someone did sample it once, it would describe one afternoon. The proportion of Lewis & Clark water to Rock Valley water arriving in Hull is set by demand, pressure and which line is carrying the load, and no one publishes that ratio.
For a homeowner that has a blunt practical consequence. Sizing a softener from a hardness-by-city table does not work here, because our own Iowa water hardness by city reference has no Hull row to give you, and no agency has published one for anybody else to copy. A ten-minute test at your own kitchen sink settles in one reading what two state databases and the city's own annual report cannot answer.
Hull used to have its own water, six wells of it. The Iowa DNR source water tracker still lists them all: Hull #1 into the Cambrian below the St. Lawrence at 1,263 feet; #2 into the Dakota at 770 feet, drilled in May 1939; #3 from 1946 with no depth recorded; #4 at 665 feet from 1959; #5 at 630 feet from 1963; and #6 at 650 feet from 1980. Every one is plugged or listed as not used, and the federal inventory names three of them bluntly as plugged wells. The last came out of service in 2008.
The reason is legible in the mineral data from that era. Total dissolved solids in the Hull distribution system measured 2,320 mg/L in May 1982, 2,340 mg/L in April 1985 and 2,170 mg/L in May 1988 — more than four times the EPA secondary standard of 500 mg/L. Those three are the whole of what the Iowa DNR portal holds for Hull on dissolved solids. All three were drawn from the distribution system itself, and all three predate the July 1997 retirement of the sample point on the plant that treated wells #4, #5 and #6.
Read those as history. They are between thirty-eight and forty-four years old and describe deep Dakota water Hull has not served in decades. What they explain is the decision: a small town facing a mineral load like that eventually stops fighting the aquifer and buys its way out. Hull finished doing exactly that on 2 May 2023, when ribbon cuttings were held at the Hull and Sioux Center meter buildings and Hull became the 17th of Lewis & Clark's 20 members to take water. The state record agrees with that timing: Hull's Rock Valley-only sample station was retired on 12 April 2023 and replaced by the blended tap.
What Hull did not do was drop its old supplier. The Rock Valley line stayed open, which is the entire reason this page cannot end with a single number.
Five federal treatment records exist for Hull Water Supply and every one of them is disinfection. The active chemical feed building at the Lewis & Clark connection runs chlorination, gaseous chlorination and chloramination. The older meter building ran chlorination with sodium hypochlorite until it was deactivated on 22 October 2018. There is no softening record, no filtration record and no aeration record anywhere on Hull's own file.
Chloramine is worth understanding if you drink from the kitchen tap. It is chlorine combined with ammonia, and utilities on long pipelines use it because it holds a residual much further down the main than free chlorine does. The trade-off is that it is slower to break down on activated carbon, so a drinking-water filter in a chloraminated town wants catalytic carbon ahead of the membrane rather than ordinary carbon, and it wants those cartridges changed on schedule. Our reverse osmosis systems are specified that way, which matters more in Hull than it does in a town still running plain chlorine.
Because the blend is unmeasured, we size in Hull from the reading we take at your sink rather than from a public figure. Every price is all-in: equipment, installation by a licensed local plumbing professional, taxes and a lifetime parts warranty.
Annual maintenance is $199 a year for a tank-RO home and $249 for a tankless-RO home. A full diagnostic service call is $199; a known-issue trip is $99 plus the part. We offer 0% financing, and $100 off for military and first responders. Ask for the written breakdown before you schedule, or start one through our instant quote.
Outside the city limits the picture changes completely. A private well north or east of Hull is drawing its own water with no chlorination, no chloramine and no monitoring. The Iowa DNR recommends testing a private well every year, and Iowa's Private Well Grants program pays for county lab testing at no cost to the homeowner. Our well water setup is a dual-tank system at $3,450, or $3,800 with tank RO, with UV disinfection at $700 and sediment pre-filtration at $500 when the readings call for them. We fit tank RO rather than tankless on a well, because high dissolved solids cost a tankless unit its pressure. Start with free well water testing.
We are licensed and insured, and our softeners are built from NSF/ANSI 44 certified components and our reverse osmosis systems are certified to NSF/ANSI 58. Installation is handled by licensed local plumbing professionals we vet, schedule and stand behind. Pricing is published and all-in, so the figure you read here is the figure on the paperwork. Distance and site conditions are the only things that can change it, and we tell you before you agree.
Most towns give you a number to argue with. Hull gives you two suppliers, one softened and one not, and no published result for the mixture. That is not a reason to guess — it is the reason to measure. We come to your house, test the water at your own kitchen tap, tell you what it actually reads that day, and leave you the numbers and a written quote at no charge. Call or text 319-319-6566, email ryan@kindwaterco.com, or book your free in-home water test.
Nobody publishes a figure. The Iowa DNR sample database holds zero hardness results for Hull Water Supply even with the date range opened back to 1900, and Hull's own 2024 water quality report prints none. Hull buys all of its water and blends two wholesalers: Lewis & Clark publishes 150 mg/L, or 8.5 to 9.5 grains per gallon, for its lime-softened supply, while the Rock Valley Rural Water District removes no hardness at all. Its individual raw wells have tested 410 to 952 mg/L, but it blends seventeen shallow wells with its two newest before delivery and nobody has ever measured hardness at that blended tap. What reaches a Hull kitchen is unmeasured, and the only way to find out is to test it.
Partly, and not by its own hand. All five EPA treatment records for PWSID IA8444063 are disinfection — chlorination, gaseous chlorination and chloramination at the active chemical feed building, and chlorination at the meter building retired in 2018. Hull operates no softener, no filter and no aerator. One of its two suppliers, Lewis & Clark, lime-softens at Vermillion, South Dakota. The other, the Rock Valley Rural Water District, treats only for iron and manganese, which leaves calcium and magnesium untouched.
Entirely from other utilities. EPA SDWIS classifies Hull as a purchased-groundwater system with two active purchase connections, one from the Rock Valley Rural Water District and one from the Lewis & Clark Regional Water System. All six of Hull's own wells — four into the Dakota aquifer between 630 and 770 feet, one Cambrian well at 1,263 feet, and one from 1946 with no aquifer or depth on record — are plugged or listed as not used, the last taken out of service in 2008.
Ribbon cuttings were held at the Hull and Sioux Center meter buildings on 2 May 2023, making Hull the 17th of 20 Lewis & Clark members to receive water. Hull kept its Rock Valley Rural Water line open rather than replacing it, so the town went from one supply to a blend of two. Iowa's own records track the change: the Rock Valley-only sample station in Hull was retired on 12 April 2023 and replaced by a station labelled as a blended tap.
A Kind Water Co softener is $2,500, or $2,850 paired with reverse osmosis. The XL softener is $2,800, or $3,150 with RO, and a standalone RO system is $800 for the tank model or $900 tankless. Every figure is all-in with equipment, installation by a licensed local plumbing professional, taxes and a lifetime parts warranty, with 0% financing and $100 off for military and first responders.
Every figure on this page comes from a public record you can open yourself.
Whole-home water softening, filtration, and reverse-osmosis drinking water — professionally installed and built to last a lifetime.
Serving Marion, Cedar Rapids & surrounding Linn County communities
Kind Water Co is a d/b/a of Zero Cap Investments LLC · 2258 Bison St, Apt B, Marion, IA 52302
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