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What is the ph of water and why it matters for your health and plumbing

Shannon
What is the ph of water and why it matters for your health and plumbing

What is the ph of water and why it matters for your health and plumbing

Understanding pH: A Simple Scale With Big Consequences

If you’ve ever tasted “metallic” tap water, fought limescale in your kettle, or wondered why some water feels “softer” than others, you’ve already had a close encounter with pH – whether you realised it or not.

pH is a measure of how acidic or alkaline (basic) a solution is. It runs on a scale from 0 to 14:

Pure water at 25°C has a pH of around 7. But the water that reaches your tap has travelled through rivers, soils, rocks and pipes, picking up dissolved minerals, gases and, in some cases, contaminants such as PFAS, heavy metals and disinfectant by-products. All these can influence its pH.

Why does this matter? Because pH quietly affects:

Let’s unpack that, starting with the basics.

What Is the pH of Drinking Water Supposed to Be?

Most drinking water guidelines recommend a pH range between 6.5 and 9.5. This isn’t just for comfort; it’s for pipe integrity and public health protection.

Here’s how major authorities frame it:

So, pH itself is not usually a toxic contaminant in the traditional sense. You won’t get “pH poisoning” from slightly acidic or alkaline tap water. But pH strongly controls:

In short, pH sets the chemical “mood” of your water – and other substances respond to it.

How pH Affects Your Health

It’s common to see claims that “alkaline water” can detoxify your body, prevent cancer or “neutralise acidity” from your diet. From a scientific and medical standpoint, those claims are not supported by robust evidence.

Your body has strong buffering systems (especially your lungs and kidneys) that keep your blood pH in a very narrow range around 7.35–7.45. Drinking slightly acidic or slightly alkaline water within normal drinking water ranges does not override that.

However, pH can still influence health indirectly in several important ways.

When Water Is Too Acidic: Corrosion, Metals and Sensitive Stomachs

Water with a pH below about 6.5 is considered “aggressive” or corrosive. It’s more eager to dissolve metals and minerals from pipes, fixtures and storage tanks. That can have health implications.

Key risks of overly acidic water include:

There is a well-documented example of this. During the Flint, Michigan water crisis, changes to water treatment led to more corrosive water entering the distribution system. This stripped protective scales from pipes and released lead into drinking water. While the crisis wasn’t caused by “low pH” alone, corrosion control – closely related to pH management – was at the heart of the problem.

In everyday UK or EU tap water, you’re unlikely to see extreme pH values. But slightly acidic water combined with old plumbing can still be a concern, especially for:

When Water Is Too Alkaline: Taste, Skin and Mineral Build-Up

On the other side of the scale, water above about pH 8.5 can bring its own set of issues, although again, these are mostly indirect rather than toxic in the strict sense.

Potential effects of very alkaline water include:

At typical tap water pH levels, these effects are usually mild. The main challenges of high-pH water show up not in your body, but in your home infrastructure.

pH, Hardness and That White Crust on Your Kettle

If you live in a hard water area, you already know the symptoms:

While hardness (mainly calcium and magnesium) is a separate parameter from pH, they interact. Alkaline conditions can encourage scale formation, because calcium carbonate is less soluble at higher pH. This won’t harm your health – in fact, calcium and magnesium are essential nutrients – but it does:

From a water treatment perspective, utilities often adjust pH deliberately to strike a balance: not so low that pipes corrode, not so high that scale becomes unmanageable.

Why pH Matters So Much for Plumbing and Pipes

Your plumbing system is essentially a long, reactive test tube that your water runs through every day. pH determines whether that test tube stays intact or slowly dissolves into your glass.

Here’s how pH affects common materials in pipes:

On the other hand, water that’s too alkaline and rich in minerals can form thick scale layers:

Water utilities manage these risks by adjusting pH and using corrosion inhibitors (such as orthophosphates). But what happens after the water reaches your property – including how your own filters and softeners alter pH – is often your responsibility.

pH and Contaminants: Including PFAS

Where does pH fit into the bigger picture of chemical contaminants like PFAS, nitrates, or heavy metals?

Two key points:

With PFAS (“forever chemicals”), pH doesn’t usually change how much is present in your tap water as dramatically as it does for metals. However, pH does matter for:

In short, pH is part of the broader chemical context that determines how easily your water can be cleaned up – or re-contaminated as it travels through pipes and fixtures.

How to Test the pH of Your Water

If you’re curious about your water’s pH, you don’t need a full laboratory. Several options are accessible to households:

For most households, combining your supplier’s data with a simple at-home check is enough to understand whether your pH is broadly within the recommended range.

What If Your Water pH Is Outside the Ideal Range?

If you measure a pH significantly below 6.5 or above 9.5 at the tap, it’s worth investigating further. Start by asking:

Then, practical next steps might include:

From there, adjustments may involve both system-level and household-level interventions.

Household Solutions: Adjusting pH and Protecting Your Home

If your water supplier’s pH is within the recommended range but you’re still seeing corrosion or scaling, the problem may lie in your internal plumbing or treatment devices.

Common household options include:

If you’re also targeting PFAS or other persistent contaminants, check carefully how a given treatment configuration affects:

A system that removes PFAS effectively but causes excessive corrosion might unintentionally increase your exposure to metals – trading one problem for another.

pH in the Bigger Environmental Picture

pH doesn’t just matter in your pipes; it matters in rivers, lakes, wetlands and groundwater. Aquatic organisms are often far more sensitive to pH shifts than humans. Many species thrive in specific pH windows, and even small changes can:

Acid rain, mining effluents, industrial discharges and agricultural run-off have all altered water pH in various regions. In some cases, that makes metals and other contaminants more mobile, increasing exposure risks downstream – including at drinking water intakes.

PFAS add another layer to this story. They are extremely persistent and can travel long distances in water. While their stability means pH alone won’t break them down, the broader chemistry of the water – including pH, organic matter and co-contaminants – influences how PFAS spread, how they’re removed in treatment plants and where they accumulate in the environment.

Practical Takeaways for Your Home and Health

To make sense of all this chemistry in day-to-day terms, it helps to keep a short checklist in mind:

pH may seem like a small number on a lab sheet, but it quietly shapes how your water behaves in your body, in your pipes and in the environment. Understanding it – and paying attention to how it interacts with contaminants from PFAS to lead – is a practical step toward safer, more sustainable water in everyday life.

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