Does Reverse Osmosis Remove Lead?

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Lead is one of the most harmful tap water contaminants – so much so that the metal was banned from use in plumbing systems in 1986. But this ban only applied to new pipes, and many homes still receive their city water from lead pipes.

Experts still aren’t sure about the long-term health effects of ingesting drinking water containing even low lead levels throughout a lifetime, but what we know so far isn’t promising. Lead builds up in the body and can eventually result in lead poisoning if intake is high enough.

You can check for lead in your water by carrying out an at-home water quality test – and if you discover an unnerving amount of lead in your sample, you probably want to remove it entirely.

Remember, however, that many DIY lead tests are not as accurate as a Laboratory Water Analysis, and that a Lab Water Test is the best way to go for not only finding out if there is lead in your water supply, but also if there are “competing contaminants” that could affect the performance of a water treatment system. You can do this with a number of water filtration techniques, but one of the best by far is reverse osmosis.

completed tap score water test
Lab water test by Tap Score

🚰 How Do RO Systems Remove Lead?

In the reverse osmosis process, water is forced through a series of multi-stage filters and a semi-permeable membrane at a high pressure.

Typically, one of the filters in a reverse osmosis system is an activated carbon filter, which is usually designed to remove lead using adsorption, physical pore size, and ionic bonding.

Ionic bonding is a chemical bond that involves the electrostatic attraction between oppositely charged ions, and is the primary interaction occurring in ionic compounds. Ionic bonds form when a nonmetal (binder/adsorbent) and a metal (lead) exchange electrons

The activated carbon pores attract contaminants like lead and chlorine, which stick to the media’s large surface area and are unable to travel onwards with water.

Though activated carbon filters can offer up to 95% of lead reduction, reverse osmosis is much more thorough than this. After traveling through the activated carbon filter, a reverse osmosis membrane is used, which removes high levels of lead, as well as other contaminants found in municipal water supplies, for example heavy metals, volatile organic compounds (VOCs), and chemicals.

Because lead molecules are larger in size than water molecules, they’re unable to pass through the semi-permeable membrane. As a result, they “bounce back” from the membrane, where they’re flushed down a drain with wastewater – and only lead-free water remains.

Closer look of the reverse osmosis membrane

📊 How Much Lead Does Reverse Osmosis Remove?

Reverse osmosis systems are so effective that they can remove more than 99% of lead. Typically, reverse osmosis treatment removes lead up to 99.1%. This is a better result than you could get from any other filtration system, including a single activated carbon filter, which removes about 95% of lead on average.

🧫 Does Reverse Osmosis Remove Other Contaminants?

The nature of reverse osmosis water filters means that they’re capable of removing much more than lead in your water supply. These filtration systems can eliminate more than 99.9% of most inorganic material, from VOCs to chlorine, heavy metals to chemicals – and even difficult-to-remove contaminants like fluoride and bacteria.

👎 Drawbacks of a Reverse Osmosis Water Filter

Everything is Removed – The Healthy Stuff Too

Because reverse osmosis water filters are so effective, they won’t just stop at removing lead and other unwanted impurities in your water supply. There’s no way for reverse osmosis filters to detect a “good” impurity amongst the bad, which means that healthy minerals that give our drinking water a pleasant taste are also removed.

While we get many of these minerals from food, you may find that drinking water tastes “flat” without them. Luckily, many RO systems come with a last-stage remineralization filter, which reintroduces the likes of calcium and magnesium back into water before it reaches your faucet.

Water is Wasted

When you send any amount of water through a reverse osmosis system, some of it will end up being wasted. The way that RO water treatment works is that contaminants that can’t fit through the RO membrane end up accumulating in the RO chamber. Unlike typical water filtration, there’s nothing for the contaminants to stick onto, so the only solution is to send them down the drain with some of the water.

During reverse osmosis, water is wasted at a constant rate from the moment you turn on your system to the moment you turn it off. The average RO system wastes around 4 gallons of water for every 1 gallon of purified water produced.

Because water is only wasted while your system is on, if you’re only using your faucet for drinking water, your water waste per day will be minimal and won’t contribute noticeably to your bills. In the case of whole house reverse osmosis systems, some companies utilize technology which wastes 1 gallon of water for every 4 to 5 gallons that are produced.

Can Be Expensive

Because they offer the highest level of water treatment, reverse osmosis systems tend to be more expensive on average than other water filters. Expect to pay between $150 and $400 minimum for one of the best RO filters on offer, with some systems even costing more than that.

The price of an RO system usually reflects its quality, so it’s worth paying that little bit more for the RO water filter with the most positive reviews.

Maintenance is Necessary

If you want your reverse osmosis unit to work for longer than a few months, you can’t avoid maintenance. The water filter cartridges in an RO filter – usually a pre-filter, post-filter and activated carbon filter – require changing every 6 to 12 months, product depending. The RO membrane can last up to 3 years, but typically requires changing after 2 years.

Replacement filters usually cost around $40-$50 for a batch of three, while replacement RO membranes cost around $20-$45, depending on which brand you go for. If you’re unsure when to change your water filter cartridges, you should find all the information you need in your user manual.

💭 Considerations for Selecting an RO System

You want a reverse osmosis unit that can remove lead from your contaminated municipal water – but there’s more to it than that. The best reverse osmosis filter for you may be very different from the best choice for somebody else. Here’s what to consider when you’re looking for a filtered RO unit for your whole family.

Tank-Based RO System

The System Type

The two most common RO systems are countertop and under-sink. Under-counter RO technology is installed under your kitchen sink and connects directly to your cold water line. You can use this type of filter to access clean water immediately from your faucet.

Countertop RO technology doesn’t require the same level of invasive installation as an under-sink unit. A countertop unit is either standalone or connected to your faucet with a flexible hose. In a standalone unit, you simply fill the machine with water and press the button to activate the RO treatment. The water will then pass through the multi-stage filtration, which will reduce contaminants, before flowing into a clean water tank ready for drinking.

Countertop RO filtered systems may be tank-based or tankless. A tank-based system stores water in a tank, and when you turn on your tap, this water flows from the tank into your glass. Tankless systems produce filtered water on demand, and can produce roughly the same number of gallons of water per minute – they’re just more space-saving as they don’t need room for water storage.

Related Content: Does a water softener remove lead? Find out here!

Your Budget

You’ll need to consider your budget in two parts: the budget you’ll need for buying an RO filter and the budget you’ll need for buying replacement filters. The majority of reverse osmosis units are multi-stage, so you’ll have more filters to think about than with a single water filter system (such as an inline filter or a pitcher filter). If you plan to use your RO unit every day, it’ll pay for itself in just a few years, but plan carefully to make sure you can budget in for those filter changes after your initial purchase.

Efficiency of the System

Though the reverse osmosis process is about as thorough as you can get at removing lead – only distillation really matches up – it’s not the most efficient filtration method out there. Every time they’re used, reverse osmosis technologies will waste a small amount of water per day, and the average wastewater to pure water ratio is 4:1.

Some systems are more efficient than others, and it’s actually more common nowadays for a unit to have at least a 3:1 ratio, with some even having a 2:1 or 1:1 ratio. But if you’d rather not waste water at all, it may be worth looking at distillation machines to remove lead from your water source instead, which is another efficacious lead removal option that produces no water waste.

Your Water Quality

Aside from lead removal, once you have a better idea of what your water contains, you might want an at-home RO unit that can do more.

Check the chlorine contaminant levels of your water source, and see if this is something you want to reduce or remove. Fluoride is another common contaminant that has health effects even in low amounts, and RO purification can help with fluoride reduction or even removal. The RO process can be used to provide lead-free water with virtually no other contamination sources, making it tastier and better for the health of your whole family.

  • Mark Timmons
    Master Water Specialist (MWS)

    Mark Timmons, a Level 6 Master Water Specialist (MWS) with over 50 years of experience in the water treatment industry, holds the highest WQA Certification since 1981, making him the USA's highest-ranking and longest-tenured Master Water Specialist. As a seasoned trainer and motivational speaker, Mark is known as "America's Water Doctor," and leverages his unique background to provide innovative water solutions to his clients in Indiana.

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