Fluoride Reduction
Removing fluoride from water can be a tricky thing to do.
The best and effective methods are as follows:
#1 Reverse Osmosis (RO): Removes up to 85-97% of fluoride alongside other heavy metals. It’s one of the most effective ways to reduce fluoride at the tap.
#2 Water distilling: The steam is then condensed back into liquid, producing purified water with significantly reduced fluoride and other minerals, heavy metals, and most contaminants.
#3 Activated alumina filters
An NSF 61-certified granular activated alumina (AA) is a specialised filter media designed to effectively remove fluoride and arsenic from drinking water. Made from aluminum oxide, AA has an exceptionally high surface area, which allows it to adsorb fluoride efficiently. In municipal water supplies, fluoride concentrations are typically around 2 ppm, and AA filters can reduce this to below 0.1 ppm.
Drinking water only
Undersink designated drinking water dual water filtration with a low flow tap will provide the best results effctively removing up to 95% of fluoride when it is new. The second filter (CTO 1 micron carbon block filter ) will help to improve the water quality and prevent any taste issues.
Whole house filtration
Best results rely on the fluoride to have as much contact time with the filter media as possible allowing the fluoride to be bonded to the highly absorbant Activated Alumina media. Example if the flowrate passing through is high due to the amount of taps running at one time the fluoride reduction rates are significantly reduced. A single flowing tap under 10lpm will provide the best reduction rates.
How water PH Levels impact Activated Alumina (AAL)
The best pH level for activated alumina to effectively remove fluoride from water is between 5.5 and 6.5.
Here’s why this pH range matters:
- Higher Fluoride Adsorption: The slightly acidic environment enhances the fluoride-binding ability of activated alumina.
- Lower Effectiveness at High pH: At higher pH levels (above 7.0), fluoride removal efficiency decreases significantly because fluoride ions are less likely to bind to the alumina surface.
Examples:
- pH 7.5:Efficiency might drop to about 30-50%.
- pH 5.5-6.5: Efficiency can reach 85% or higher.
Summary:
There is no definitive time frame for when an AAL fluoride filter should be replaced, nor a guaranteed lifespan. If unsure, periodic water testing or filter replacement based on usage are recommended, but often not feasible.
How much water do you use?
What is your PH level?
Having a good quality variable density sediment filter and a 1-micron Matrikx carbon filter before the activated alumina (AA) filter can significantly extend the lifespan of the AA media by 30-50%, although it doesn't directly affect its fluoride adsorption capacity.
Here's why:Prefiltration in whole house systems prolongs the lifespan of the AAL media.
- Preventing clogging from debris.
- Reducing fouling by organics, chlorine, or heavy metals.
Fluoride Reduction Using Bone Char Method
Carbonized bone char, a material produced by heating animal bones, is effective at reducing fluoride and heavy metals from town water.
Here's a more detailed explanation:
Fluoride Removal:
Bone char's hydroxyapatite structure (a form of calcium phosphate) allows it to effectively adsorb fluoride ions from water.
Heavy Metal Removal:
Bone char can also remove various heavy metal ions, such as lead and arsenic, from water.
Mechanism:
The high surface area and porosity of bone char enable it to adsorb a wide range of impurities, including fluoride and heavy metals.
Other pollutants:
Bone char is effective at removing cesium, ammonia, and organic compounds in addition to fluoride. It works best in a filtration tank system with a manual or automatic backwashing head.
Media Costs
For a typical household, bone char media lasts around 12-18 months before needing replacement. The estimated cost for new media is approximately $70 per kg
A basic system with a manual backwashing head starts at around $2500
Activated Carbon Pre filter
Carbon filters are used to remove or reduce a variety of contaminants from water. Activated carbon filters are particularly good at removing chlorine, tastes, odours, pesticides, volatile and organic carbons, dissolved colour and chloramines.
Where it is necessary to treat all incoming water [point of entry - POE], the High Flow Carbon Series presents the best cost effective solution to handle the much higher flow rates and provide a longer life throughput.
Features
With automatic back-flushing, the need for maintenance is all but eliminated. Replenish carbon annually or when chlorine, taste, odours or targeted contaminants start to break through.
Activated carbon is best installed before the bone char
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Carbon Before Bone Char: If you're dealing with chlorine, VOCs, or organic compounds, placing activated carbon before bone char helps protect the bone char media from fouling and extends its lifespan. This setup is ideal for municipal water supplies where chlorine is present.
For a typical household, with activated carbon, the estimated cost for new media is approximately $40 per kg
A basic system with a manual backwashing head starts at around $1600
