Our guarantee
We GUARANTEE to give you your money back - even years from installation - if our LimeStops fail to stop limescale.  We are the ONLY manufacturer to do this.  We can do it because we know that our LimeStops work.  And in 20 years of manufacture, we have NEVER had to give anyone their money back!  There has never even been a single claim made.  That guarantee is your assurance that you are purchasing something which you KNOW will work.  Manufacturers of other 'Limescale inhibitor' do not offer this guarantee.  That should tell you everything you need to know.  But in case it doesn't...

In many areas of the UK, such as the Thames Valley, Kent and East Anglia in particular, rain water will pass through rocks that contain calcium and magnesium.  The water that filters through these rocks will partially dissolve these minerals.  Your water supplier will remove this underground water, clean it, and send it to homes across your region.  But the dissolved minerals remain.  When the water is heated (especially over 63 degrees C) the calcium deposits will fall out of the water and adhere to surfaces.  This is what's commonly called 'limescale'.  It’s highly damaging to water heating equipment and costs consumers millions of pounds per year.

However, you don’t have to resort to fancy ideas of protecting water systems from the damaging effects of limescale.  Water softeners are good products for defeating limescale.  But they are expensive, and require constant salt replenishment and maintenance.  The problem with non-physical water conditioners, such as those that use electronic signals, is that they seem largely unproven, and manufacturers of these units are conspicuously reluctant to offer a money-back guarantee if they don’t work.  Polyphosphate inhibitors almost exclusively use a ‘dosing’ unit which has tiny holes for the water to flow in and out.  However, the holes block up with the powdery polyphosphate!

We have carried out research for many years on what works and what doesn’t.  Over thirty years of attending to hot water appliances that are encrusted with limescale has revealed that there really is only one choice - Siliphos, silicate-polyphosphate.  A Siliphos dispenser doses the water with silicate-polyphosphate.  So in 2003 we set out to find the perfect Siliphos dispenser for combi boilers - and, after constant improvement, the CombiBuddy (and LimeStop) were the result.  Since then, we’ve gone on to produce a range of limescale inhibitors over the years - backed by our infamous guarantee!

Siliphos (read more at the foot of this page) is a widely-trusted food-grade material proven time and again to inhibit limescale formation.  Its ability to combat limescale deposits is really quite remarkable as it both lays down a protective layer on the walls of the supply piping AND inhibits calcium deposits.  Replacement of the units (every 2 years - at a discounted rate) can quite literally be a 5-minute job!  We’ll even remind you when replacement is due.  For standard limescale protection, install a LimeStop 800.  If you want to protect a whole-house installation with more than three bedrooms, then opt for the LimeStop 1000.  The LimeStop 1500 is really only manufactured for commercial use.


What is the LimeStop limescale inhibitor?
The LimeStops inhibit limescale from forming.  Some people call such devices ‘water conditioners’.

The majority of limescale inhibitors don’t work, do they?
No, they don’t.  Many such devices use magnets, electrolytic action, or electronic waves.  If they worked, then the manufacturers would offer you your money back on performance...but they don’t!  Here’s the ‘guarantee’ on a popular-selling ‘limescale inhibitor’...
We guarantee that your ********** will work for you. If you are not satisfied with the performance after 3 months continuous use, please contact us within 30 days of the end of this period
Really?  Four months?  It follows then that after just four months, when you find that this product (which costs more than £100) doesn’t actually work, then you won’t get your money back!  Here’s another...
If after six months of continuous use, you are dissatisfied with the performance of your water descaler, you may return it for a full refund
Again, after six months you’ll be unlucky when you discover it hasn’t worked!  What good is this?  If it really did work, then the manufacturer would surely be happy to give you your money back no matter when you made your claim?

So why is the LimeStop different?
The LimeStop range uses Siliphos - silicate-polyphosphate, so it’s classed as a ‘physical’ limescale inhibitor, in that it actually uses something to inhibit limescale – there are no smoke and mirrors!  Siliphos is remarkable stuff - able to positively halt limescale formation.

Is that why you guarantee it?
Yes, if you research ‘limescale inhibitors’ (on the internet) you’ll find that manufacturing companies of these devices will NOT give you your money back, years down the line, if they don’t work!  WE WOULD.  We can offer such an amazing guarantee because Siliphos really does work, even in very hard water.

Like where?
LimeStops have been installed in most parts of the UK, and have been sold in Ireland, France, Spain, Belgium, and Barbados.

What’s inside that inhibits limescale?
Siliphos - a food grade material called silicate-polyphosphate.

How does it inhibit limescale?
As water flows through the LimeStop it flows over the Siliphos particles - which give up a slight amount of their coating.  Siliphos inhibits limescale in two ways.  First of all the polyphosphate makes the calcium molecules stay in suspension, rather than stick.  Secondly the silicate lays a layer on the walls of pipes etc.  This too helps to inhibit limescale sticking.

Does it remove limescale that is already present?
Yes, but it takes time.

Does the Siliphos 'run out' of its effectiveness?
It degrades, that’s why a replacement is required.  We will send you a reminder.

So what will be the continual cost of the LimeStop?
The LimeStop 500 costs from as little as 10p a day!  The LimeStop 800 costs from just 11p a day, and the LimeStop 1000 just 12p a day.

Is replacement a straightforward swap?

Should I use a plumber to do that?
You could, but it really is quite easy.

Isn’t there a rival product to the LimeStop - one where you just replace the Siliphos?
Yes, but both the LimeStop 500 and 800 still work out cheaper (as does the LimeStop 1000)!

Is the water drinkable?
Yes, Siliphos is a non-hazardous, food-grade material.  It conforms to EN1208:2005 and WHO standards for drinking water supplies.  Unlike artificially-softened water, it's safe for babies too.

Is it classed as a water softener?
No, the hardness is still there, it's just suspended.  This is true of all limescale inhibitors; if a water conditioner doesn't actually remove the calcium, then it's not a water softener.

If the treated water is then stored, will it still be effective?
Yes, but the sooner the stored water is used, the better.

I don’t have a 15mm mains water connection
No problem, the LimeStop 500 is (primarily for combi boilers) 15mm.  The LimeStop 800 is available in either 15mm or 22mm for the same price, as is the LimeStop 1000.

What do I need to install it?
You may need some simple fittings, copper tube, a tube cutter, and basic tools.  You are also required to install a non-return valve - though your mains supply may already have one.

Your instructions say not to fit the LimeStop too close to a heat source, why?
Warm water back-feeding down the supply will degrade the Siliphos.  Its period of effectiveness would be less.

Is it easy to fit?
Yes, very.  Fitting should take no more than 30 minutes.

What if there is hardly any pipework to fit it on?
That’s no problem.  All you need to do is re-locate the LimeStop away from the piping.  You could route the piping both to and away from the LimeStop with flexible hoses, so you really need just 3” of piping.

Can I fit it in a cupboard?
Yes, but not if the ambient temperature is above 30 degrees C for the same reasons as above.  Also, fit it low down in the cupboard where the cold mains enters, as it would be the coolest part of the cupboard.

Will I still get limescale around my showerhead?
Most possibly, yes.  This is because although the Siliphos-effect will stop your shower scaling-up, 'still' water (water that doesn’t move) will be left on the showerhead and around taps etc.  The effect will be lost and deposits may well occur.  But these can simply be wiped away, as the deposits aren’t sticky.  Marks on glass shower doors can often be magnesium deposits.  These are difficult to shift and will even occur if you had an ion exchange water softener.  Glass shower and bath panels should be wiped daily with a wiper blade.

What will the LimeStop protect?
The LimeStop range is made for ‘mains’ water appliances, such as mains-pressure thermal store hot water heaters, washing machines, dishwashers, shower mixer units, etc.

What about ‘Megaflow’ type units?
These use a store of hot water, but they are ‘heat banks’ and not thermal stores.  We can only state that the sooner the water is used after running through the LimeStop, the better.  The LimeStop 800 is perfect to protect thermal store hot water cylinders.

Will my water pressure be reduced?
All the LimeStops are through-flow units, and you would not see any noticeable drop in water pressure or flow after fitting.

Will the LimeStop withstand high water pressures?
Yes, they very robust units, able to withstand 6 bar pressure, with twin ‘O’ rings in the case of the LimeStop 1000.  However, it is still recommended that you install a pressure limiting valve prior to the LimeStop (set to 3 bar) if you suspect that your pressure is very high (over 4.5 bar).  You may already have a pressure limiting valve fitted to your water supply - many homes have.

Can you supply larger (doubled-up) versions?
Yes, we can.  Just ask.

What is limescale?
It's dissolved rock.  Rain water dissolves the calcium and magnesium out of the rock.  This water is then treated and sent to your home.  When the water is heated, the dissolved particles re-solidify and stick to the walls of the heat exchanger.  It will do this at low temperatures, but it really begins at anything above 63 degrees C.

Is limescale harmful?
To your heating appliances, yes, very!  Even a tiny coating of it will reduce the efficiency of your appliance, meaning your energy bills will be higher.  It also causes premature failure of key components.  However, to your body, it is beneficial.  Remember, water softeners remove this beneficial calcium, the LimeStop doesn’t.

Why is the LimeStop better than other limescale inhibitors?
The LimeStop requires no electricity or maintenance - just replacement.  It doesn't use questionable electromagnetic waves.  It uses a time-proven material that we feel good enough to offer our performance guarantee of your money back.  And you don’t have to fiddle with large 'O' rings and wet Siliphos - you simply replace the cartridge housing!  You may be aware of a very similar unit to ours, but that device requires 6-monthly topping up, with annual cleaning and Siliphos replacement - see foot of this webpage.  You don’t have to do that with ours!

Do you guarantee that the LimeStop works?*
Yes, we do.  Our guarantee is that stated formally below.  We believe all limescale inhibitors should carry a performance guarantee.  Don't buy one that hasn't got a money-back guarantee.  Ours have, and we’re very proud of it.

Have you ever had to give anyone their money back due to re-scaling?
No, never...in 20 years.

Do you give a discount if I buy more than one?
We can only offer a discount if you buy 3 or more.  We offer a substantial discount for the purchase of 10 or more.  Please email us.

Can you install the LimeStop for me?
We can do this - the labour charge is usually around £69 plus any materials used - but only in the RG postcode area, sorry!  However, any plumber can do it, and it’s not at all difficult for the average diy-er.  You may only need a hacksaw and a spanner!

How quickly can I get one?
We usually send our LimeStops by Royal Mail.  This is usually a 48 hour service, though this obviously cannot be guaranteed.  Our deliveries are free ONLY to UK mainland addresses.  We no longer deliver to the EU.  If you require your LimeStop urgently, please let us know when you order, and we can send by overnight courier. There is a £10 charge for this service.

Can I come and buy a LimeStop at your door?
Yes, if you’re close to us (we’re in Reading, Berkshire) but call ahead first on 07702316157.

What about the CombiBuddy and the LimeStop TS?
The CombiBuddy and BoilerBuddy were both replaced by the LimeStop 500 (and contain more Siliphos than either of those previous two for a cheaper price!).  The LimeStop TS is replaced by the LimeStop 800 which can be installed horizontally, and is much cheaper than the LimeStop TS.  The stainless steel LimeStop (containing 1 kilogram of Siliphos) is still available to order (please email us).

Why are the LimeStops not available in Plumber's Merchants?
This is something currently being considered.

Why we are not on Amazon.
We don’t support Amazon and its restrictive practices.  We believe in supporting BRITISH retail outlets.

Why we are not on Ebay.
We don’t support Ebay and its poor customer support practices.

Why we will NOT offer PayPal.
PayPal’s charges would make our products more expensive.

What the LimeStop is, and what it isn’t:
The LimeStop will stop limescale forming on the inside of pipes, etc.  It is not a water softener.  The ‘hardness molecules’ are still there, but the LimeStop WILL stop limescale by combining these molecules together to come out in the water - not sticking to heat exchangers or pipes.  That’s how it works.

Price increases.
The prices of our products do increase from time to time due to the increase in costs which we incur. Prices last increased on April 1st 2023.  The LimeStop 500 price increased in price by 7.5% (from April 2022).  The LimeStop 800 increased in price by 5%.  The LimeStop 1000 increased in price by 11%.  We try to limit our price increases to annually if we can.

The guarantee:
The guarantee against ‘scaling-up’ is dependent on the LimeStop being installed for 30 months and at least one replacement.  If the protected appliance/s* should ‘scale-up’ to the detriment of water flow (we would require proof to satisfy such an occurrence), then we would return the original purchase price of the LimeStop to the original purchaser.  Your statutory rights are not affected.
*Protected appliance/s: The unit purchased must be stated as suitable for its application.

The quality of Siliphos meets the international standards ISO 9001, NSF, FAO/WHO and FDA.  The National Hygiene and Nutrition Centre permits the use of Siliphos for the treatment of drinking and domestic water. Siliphos is a calcium polyphosphate (silicate-polyphosphate) medium which is made up of well-balanced silicates and inorganic phosphates.  It is even safe for babies to consume in drinking water (artificially softened water is not).

Advantages of Siliphos

...protects industrial water systems, utilities, hotels, public buildings, homes, etc. from scale and corrosion;  
...prevents the formation of so-called 'brown water';
...reduces the cost of repair/replacement of water systems equipment and extends their service life;
...saves energy;
...does not require electrical installation;
...easy maintenance.

Due to the precise concentration of polyphosphates, Siliphos prevents the formation of scale, deposits and corrosion.  The phosphates contained in Siliphos are a well-balanced blend of dietary organic phosphates, which are approved for drinking water treatment.  Phosphates slow down the cathode and corrosion processes, creating a synergistic effect.  Thanks to the successful combination of the corrosion-absorbing properties of the phosphates and silicates included in this product, the thinnest protective film is created on the metal surface, reliably protecting it from corrosion.  It is very important that a very low minimum concentration of Siliphos (2-3 mg/l) is sufficient for reliable protection against corrosion and scale formation.

Deceleration and descaling of ‘scale’

Siliphos slowly dissolves and removes metal deposits previously formed in the pipes.  It cannot be said that Siliphos destroys scale in the full sense of the word.  This reagent protects against the formation of new iron oxide/hydroxide deposits and softens accumulated deposits, which are gradually washed away by water. The time required to remove deposits depends on a large number of factors, including the number and composition of deposits.  The process can take from 4 days to 6 months and longer.  Typical brown scale (iron oxide, hydroxide) can be either completely removed or partially removed.  However, it is very difficult to remove white deposits of calcium carbonate or silicates.  In most cases, it is only possible to stop their further formation.  Defective surfaces of the walls of old pipelines are covered with soft iron oxide deposits. The water treated with Siliphos makes these deposits hard, thus preventing the defects (holes, small cracks) from increasing in size.  This is a unique feature of several types of phosphates in Siliphos.

Preventing the formation of 'brown water'

The brown colour of the water (in soft and hard water areas) can be prevented by using Siliphos.  This effect is important in the initial stage of water treatment, when the water contains a certain amount of Fe3+.  Siliphos is absorbed by iron oxide/hydroxide particles, thus protecting against the agglomeration of these particles and darkening of the water.

Efficacy of Siliphos
The effect of Siliphos in preventing limescale formation is quite remarkable, and it is the ONLY medium which works at preventing limescale - short of an ion exchange water softener.  Due to its reliability in preventing limescale formation, Scalgon (through its LimeStop range) is able to provide a guarantee of your purchase money back if the product didn't work at stopping limescale.  For 209 years, since we first developed our first limescale inhibitor using Siliphos, we have NEVER had to provide any money back under that guarantee.  Indeed, there has never even been a single claim made.