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HARD WATER STAIN REMOVAL
Hard water stain removal for north metro windows
White mineral spots lifted from your glass with an acid treatment, after a normal cleaning and one test window.
Hard water spots are the calcium and other dissolved minerals that stay on glass when sprinkler or hose water dries. Glass House removes them as an add-on to a window cleaning: the glass is cleaned first, one window is tested, and an acid treatment then lifts the bonded scale.
North metro water is very hard, and every sprinkler or hose cycle that reaches a window leaves another layer of minerals. Caught early, the spots come off. Left for seasons, they bond and eventually etch the glass, and etched glass cannot be restored by cleaning.
HONEST BEFORE WE START
We clean the glass, test one window and tell you what will lift. If the glass is etched, you will hear it from us first.
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Insured to $2M
Owner-operated
Based in Ham Lake
WHY IT HAPPENS HERE
Very hard water, city after city
Rainwater absorbs carbon dioxide in the soil and becomes a weak acid that dissolves calcium and other minerals from Minnesota's limestone and dolomite. Hardness is measured in PPM (parts per million).
180 PPM
is where the USGS classifies water as very hard. Every city on our list that publishes a figure is above it.
375 PPM
of hardness in Rogers city water, about double that line and the hardest on our list. Blaine runs about 310 to 360 PPM.
100%
of Ham Lake homes are on private wells, so sprinkler water reaches the glass exactly as it comes out of the ground.
0 PPM
is what our rinse water reads, so our own cleaning never leaves mineral spots behind.
Sources: USGS, Hardness of Water; City of Rogers and City of Blaine water pages, converted to PPM; Minnesota DNR, Blaine–Ham Lake well interference fact sheet (2023).
YOUR CITY'S WATER
Hardness and watering rules, city by city
Here is each city's published hardness, measured against the 180 PPM line where the USGS classifies water as very hard, along with its lawn watering rules.
CITY
WATER HARDNESS
CITY WATERING RULES
Ham Lake
Private wells at every home, so it varies by well
No city water system
Andover
About 220 PPM on average
Odd/even May 1 to Aug 31, no watering noon to 6 p.m.
Blaine
About 310 to 360 PPM (2023)
Odd/even all year, none 10 a.m. to 6 p.m. from May 15 to Sept 15
Anoka
Not published by the city
Odd/even June 1 to Sept 1, none 10 a.m. to 7 p.m.
Coon Rapids
About 275 to 310 PPM
Odd/even June 1 to Aug 31
Ramsey
About 255 to 290 PPM, which the city calls very hard
Odd/even Memorial Day to Labor Day, none 10 a.m. to 8 p.m.
Lino Lakes
About 255 PPM
None 10 a.m. to 6 p.m. all year, odd/even May 15 to Sept 15
Circle Pines
About 310 PPM
Odd/even June 1 to Aug 31, none 10 a.m. to 7 p.m.
Hugo
258 PPM
Odd/even days, in place since 2001
Rogers
About 375 PPM
Odd/even May 1 to Sept 30, no city water on lawns 10 a.m. to 6 p.m.
Sources: USGS, Hardness of Water; each city's water, watering-restriction and FAQ pages and drinking water reports (Andover, Blaine, Anoka, Coon Rapids, Ramsey, Lino Lakes, Circle Pines city code and Centennial Utilities, Hugo, Rogers). Hardness is shown in PPM, converted from each city's published figure where needed. Rules shown are for city water customers and can change, so check your city before you water.
THREE STAGES
The three stages, and which ones come off
How far a deposit has progressed decides whether it can be removed, which is why the answer comes only after the glass is clean.
1. Surface film
Fresh deposits sitting on top of the glass that have not yet hardened. A normal professional window cleaning removes them, with no acid treatment needed. Catching spots at this stage, and keeping sprinklers off the glass, is the easiest way to keep windows clear.
2. Bonded scale
Hardened minerals chemically bonded to the surface of the glass. Normal cleaning no longer moves them, and this is the stage our acid treatment is designed for. The glass beneath is still intact, so removal is usually well worth doing.
3. Etched glass
The minerals have bonded into the glass itself and taken microscopic material with them, so the damage is in the glass rather than on it. No cleaner can put that material back. The only remedies are professional polishing with cerium oxide or replacement.
BEFORE AND AFTER
Hard water spots, before and after
BEFORE
A sliding glass door covered in white hard water spots, with the Glass House van reflected in the glass.
AFTER
The same sliding glass door clear after hard water stain removal, reflecting the Glass House van and equipment.
HOW WE REMOVE IT
Clean first, test one window, then treat
Judging a hard water stain on dirty glass is guessing. The first cleaning removes everything else and leaves only the stain.
TINTED WINDOWS
Window tint never receives an abrasive, because an abrasive scratches the film. Tinted glass is cleaned with a non-abrasive applicator and a squeegee instead. That removes nearly all soiling, but hard debris, including bonded mineral spots, and anything behind the tint cannot be removed, so please mention tint when you book.
01
Clean the windows normally
Every window is cleaned by our usual method first, removing dirt, film and construction debris. What remains afterward is only the mineral stain, and that is the only reliable way to judge how far it has progressed.
02
Test one window
The treatment goes on a single pane first, applied directly to the glass, starting at the top and working down. You see the result on that window before any other pane is treated, and before you commit to the rest.
03
Agitate and dwell
The treatment is an acid, worked into the bonded scale with an abrasive. It then dwells for about 10 minutes, giving it time to work on the minerals before the glass is cleaned again.
04
Clean it again
The window then receives a second full cleaning, which removes the treatment along with the loosened minerals. Heavy scale sometimes takes a second application before the pane is finished.
05
A clear answer
If spots remain after two applications, the glass is etched, because the stains sat untreated too long. We tell you plainly and stop treating glass that cannot respond. It is also the best reason to deal with the next spots early.
PREVENTION
How to keep hard water spots off
SPRINKLERS
Aim away from glass
Adjust each head so it waters the lawn rather than the windows. Of everything on this list, it makes the biggest difference.
HOSES
Mind the overspray
Filling pools, washing cars and watering flower beds near the house all put mineral-laden water on the glass. Keep that spray pointed away from the windows.
IRRIGATION WELLS
Untreated water
A private irrigation well bypasses any city treatment, so its water reaches the glass carrying every mineral it held underground. Aim those heads with extra care.
TIMING
Catch it early
Surface film comes off with a normal cleaning. Left for seasons, it hardens into bonded scale and eventually etches the glass, which no cleaner can reverse.
The watering rules above apply to city water customers. In Ham Lake, where every home is on a private well, there is no city schedule at all, so the aim of each sprinkler head decides how much water reaches the glass.
HOW PRICING WORKS
An add-on, priced after a test window
YOUR HARD WATER JOB, AT A GLANCE
ADD-ON
Window cleaning first
From $240
The glass is cleaned normally so the stain can be judged
Test window
Always first
One pane is treated first, so you see the result
Hard water stain removal
Quoted
Added once we can see how far the stains have progressed
If the glass is etched
Honest answer
You will hear it plainly, before the rest are treated
Added to any window cleaning
Test first
Hard water stain removal is quoted as an add-on to a window cleaning, because its severity can only be judged on clean glass. Carson tests one window first and tells you what will lift before the rest are treated. Window cleaning package minimums start at $240.
WAYS TO SAVE
Service Plan members
25% off any other work, holiday lighting included
Veterans
10% off any service
Same-day neighbors
15% off for both households
Preferred day
Another 5% off on top of any other saving, up to 25% in all
Seniors 65 and older
$50 off
Three projects together
10% off
Discounts don't combine — you receive whichever single saving is largest. Then a Preferred day can take another 5% off, up to 25% in all (Service Plan members aren't capped).
This season’s flash sale is shown at the foot of every page.
GUARANTEES
What backs the work, word for word
These are printed word for word on your quote, your work order and your invoice.
INCLUDED
Reapplication Guarantee
All stain removal services include a reapplication guarantee: when a stain needs more than one application, the follow-up application is part of the job, not an extra charge.
INCLUDED
Workmanship Standard
If we miss an area or leave normal cleanable residue, tell us and we'll re-clean or touch it up. Our guarantees cover the cleaning result — not repairs, replacements, permanent stains, or conditions that can't be safely corrected through cleaning.
Every stain job still begins with a spot test, and we charge only for work we can complete.
WHAT IS INCLUDED
What hard water removal includes and excludes
Hard water treatment removes bonded mineral scale from glass. Damage within the glass, and the water that caused it, fall outside what cleaning can change.
INCLUDED
In every hard water treatment
• A normal window cleaning first, so only the stain remains
• One test window, so you see the result before we continue
• An acid treatment from the top down, worked in with an abrasive
• About 10 minutes of dwell, then a second full cleaning
• A second application on heavy scale
• A clear answer if the glass is etched
NOT INCLUDED
Outside hard water removal
• Etched glass, which only polishing or replacement can fix
• Abrasives on tinted glass, which receives a non-abrasive clean
• Prevention of new spots, which depends on sprinkler aim
• Iron stains on siding and concrete, a separate service
EQUIPMENT AND METHODS
Acid on the stain, pure water after
The treatment is an acid, applied straight onto the glass and worked in with an abrasive. The cleanings before and after use our standard methods: a T-bar and squeegee by hand, or a water-fed pole that rinses with 0 PPM pure water and reaches up to six stories, so the work leaves no new mineral spots behind.
SAFETY AND CARE
Safe for your glass and your family
Hard water removal puts an acid on your windows, so it follows the same safety rules as the rest of our stain work.
PROTECTIVE GEAR
Gloves, respirator and glasses
The treatment is an acid, so it is always applied in rubber gloves, a respirator and safety glasses. The same gear is used for every acid treatment we perform, from hard water on glass to iron on concrete, because the rule does not change with the surface.
CHEMISTRY
Kept apart from bleach
Acid and bleach-based cleaners are never mixed and never used back to back without a full rinse and dry, because together they produce chlorine gas. If the siding below a window also needs washing, the order of work is planned so the two never meet.
CONDITIONS
Never left to dry
Like most stain chemistry, the treatment is used above 50°F and out of direct hot sun. It is never allowed to dry on the glass: once its dwell time ends, the pane receives a full cleaning.
SURROUNDINGS
Plants below the windows
Landscaping beneath the windows is wet down before, during and after the treatment. Any drip or overspray that lands on a pre-wet surface is diluted to the point of being harmless, which is how plants come through the work unharmed.
THE OWNER
Why Carson tests one window first
Glass House is owned and run by Carson Brenny, with no crews, subcontractors or handoffs. He grew up in Ham Lake, where every home is on a private well, went to Blaine High School and has worked full-time in exterior cleaning since 2020. He quotes each job, does the work and walks it with you at the end.
White spots on windows usually mean a home is on the same very hard water as its neighbors, not that anything was neglected. Some spots come off and some have already etched into the glass, so Carson tests one window, shows you the result and lets you decide before you spend anything more.
IN CARSON'S WORDS
“It's my neighbors' homes: their biggest investment, one of the places they spend the most time, and where the people they care about most live. It's something everyone should enjoy, and I believe that.”
Carson Brenny, owner
✓
A test window before the rest
✓
Up to two applications on stubborn scale
✓
Clear answers about etched glass
WHERE WE WORK
Hard water stain removal across the north metro
Glass House is based in Ham Lake and removes hard water spots from windows throughout Anoka County and the Twin Cities north metro.
Each city page covers local conditions. The surrounding north metro is served as well, and we travel farther for a small trip fee.
HARD WATER QUESTIONS
Hard water stain removal FAQ
What causes the white spots on my windows?
They are calcium and other dissolved minerals left behind when sprinkler or hose water dries on the glass. The water evaporates, the minerals stay, and every watering cycle adds another layer. North metro water is very hard, and private wells bypass any city treatment, so spotting is common wherever spray reaches a window.
Can every hard water stain be removed?
No. Surface film comes off with a normal cleaning, and bonded scale usually lifts with our acid treatment. Etched glass is different: the minerals have damaged the glass itself, and no cleaner can reverse that. Etched glass can only be professionally polished or replaced, and we will tell you if that is what we find.
Why do you need to clean the glass before quoting?
Severity only shows once the glass is clean. Dirt, film and debris hide how far the minerals have progressed, so we clean the windows normally, test one pane and price the treatment from what we actually see. That way the quote reflects your glass rather than a guess.
Will the spots come back?
They will if the water keeps reaching the glass. The treatment removes the minerals that are there, but a sprinkler head that still hits the window lays down a new layer with every cycle. Re-aiming the heads toward the lawn is what keeps the result.
Does the Streak-Free Guarantee cover hard water?
No. The Streak-Free Guarantee covers streaks and workmanship spotting from our cleaning, reported within 72 hours. New hard water and sprinkler spots come from water reaching the glass after we leave, so they fall outside it, as do new dirt, pollen and sap.
Can you remove spots from tinted windows?
Tinted windows are cleaned with a non-abrasive applicator and a squeegee, because an abrasive would scratch the tint. That method removes nearly all soiling, but hard debris, including bonded mineral spots, and anything behind the tint cannot be removed. We will tell you this before any work begins.
Is hard water the same as iron staining?
It is the same water, but a different stain. The calcium leaves white spots on glass, while the iron in that water oxidizes into orange stains on siding and concrete. Iron requires different chemistry and is handled by our Iron Stain Removal service.
Can I remove the spots myself?
Fresh film often comes off with a thorough cleaning. Bonded scale needs an acid-based product, rubber gloves, eye protection and a test on one corner of the glass first. Never use an acid product where bleach has been used without a full rinse and dry, because the two produce chlorine gas.
