The danger of tap water comes from agricultural runoff and industrial chemical waste that leaches into our water supply. Pesticides, nitrates, PFAS, pharmaceutical residues, and volatile organic compounds (VOCs), show up in levels hundreds to thousands of times higher than health guidelines recommend. While municipal systems meet federal “legal limits,” the health guidelines are often much stricter. This means what’s considered safe to drink on paper can still harm health over decades. I live in America. The country that’s created one-third of the world’s billionaires, yet we allow nearly a thousand times more cancer-causing chemicals in our water than allowable health guidelines. Here’s what’s in the tap water where I live.
These chemicals are linked to:
- Hormone disruption (fertility, thyroid function, and lower testosterone)
- Immune suppression
- Cancer risks
- Metabolic dysfunction
So let’s break down how to optimize every single drop of water that touches our body.
Drinking water
To see the differences first-hand, I tested my own tap water, Brita pitcher, and AquaTru reverse osmosis using a TDS meter. To expand the comparison, I also included data from electronicsNMore on YouTube, who ran detailed COD, TOC, UV, and EC measurements across many bottled spring water brands. Here’s how the numbers came out:
What the Measurements Mean
- COD (Chemical Oxygen Demand):
A measure of how much oxygen would be required to break down organic and inorganic matter in the water. Higher COD usually indicates more organic pollution (waste, runoff). - TOC (Total Organic Carbon):
The amount of carbon from organic compounds in the water. This is often used to track agricultural waste, pesticides, and natural organic matter. Lower is better. - TDS (Total Dissolved Solids):
The combined total of all inorganic salts and small amounts of organic matter present in the water (measured in ppm). This is the most common number people track. It includes minerals, salts, metals, and contaminants. - UV275 (Ultraviolet Absorbance at 275 nm):
A test that shows how much UV light the water absorbs at 275 nanometers. It’s used as a marker for organic contaminants like pesticides or pharmaceuticals. Lower numbers mean fewer contaminants. - EC (Electrical Conductivity):
A measure of how well water conducts electricity, which depends on the concentration of dissolved salts and ions. Higher conductivity = more dissolved substances. - Value (Overall Score):
Rating water quality out of 100. Higher numbers mean cleaner water by their standards.
From all the testing, Tap water came out the worst. Reverse osmosis (AquaTru) was by far the best option. Among bottled waters, Voss and Icelandic stood out as the cleanest choices, while others like Evian, Fuji, and aqua panna carried heavier dissolved solids.
Cost comparison
Additionally, the long-term savings from RO are enormous. While reverse osmosis systems do have a higher upfront cost. The AquaTru countertop unit, for example, is about $449. But compare that to bottled water: if you’re buying spring water at $5 per gallon and drinking just 3¼ gallons a day, that adds up to ~$5,900 every year for clean water. A standard RO system, by contrast, might cost ~$1,100 up front with filter replacements of around $260 per year. Over 5 years, RO totals up to ~$2,140, while bottled water comes to ~$29,500.
Pros & Cons RO and bottled water
That said, there is a benefit of convenience with bottled water. You just grab and go. With reverse osmosis, there’s a small routine: every night, I prep about a gallon of water, usually going through a tank and a half each day. It’s a little work, but the trade-off is endless clean water at a fraction of the cost. Now one thing we haven’t touched on yet is plastics. Beyond chlorine and heavy metals, plastic particles are now being detected in bottled water, tap water, and even human blood. [Source 1,2,3] This is where reverse osmosis shines: it’s one of the few systems that can actually filter out these microscopic particles. On the other hand, some people raise concerns that RO water is “too clean” (similar to distilled water) and could strip minerals from your body. But the reality is, the minerals you get from water are negligible compared to food. A plate of vegetables delivers more calcium and magnesium than you’d get from drinking liters of mineral water. Still, for taste and balance, many RO systems now include re-mineralization filters. For example, AquaTru has a mineral cartridge that adds back calcium and magnesium after purification.
Shower filters
Most people only think about the water they drink. But your skin is the largest organ in the body, and it absorbs chemicals every time you shower. Hot water opens up pores, and volatile compounds like chlorine and chloramine can also be inhaled through steam, entering directly into the lungs.
When I tested the Aquasana shower filter, I did see a drop in TDS readings: from about 190 ppm down to 80 ppm. That’s roughly a 58% reduction in dissolved solids. For shower water, this is a big improvement because it will have less chlorine, fewer chemical byproducts, and noticeably softer water on the skin. Personally, it made me feel less dryness on my skin.
One note: when you first install the shower filter, it will often emit black water at the start. This is just excess carbon residue flushing out of the cartridge and goes away after a 15-30 seconds.
Under-Sink Filters
I also tested an Aquasana under-sink filter to see how it compared. On paper, it should have removed chlorine, lead, and other contaminants. But when I measured the water particles with a TDS meter, the ppm reading was virtually the same as tap water. This reinforced for me that reverse osmosis under the sink option is the best solution for those wanting to optimize the full set.
“For apartment living, things get tricky. Most buildings don’t allow self-plumbing, which rules out under-sink RO units. Faucet-mounted filters exist too, though I haven’t tested them yet. I plan to run a full test soon (update coming).
If you own a house, the gold standard is a whole-home or under-sink reverse osmosis system that feeds both your kitchen and bathroom. That way, you’re covered for drinking, cooking, and even brushing your teeth with clean water. Expect to pay $2,000 –$6,000 for a full install. And if you’re building a house from scratch and want every pipe filtered (even the toilets) that level of integration can run $100,000–$200,000.
Final thoughts
AquaTru RO: The upfront cost is worth it, and it avoids the vague scoring issues you see with bottled brands.
VOSS: Yes, but only for travel. A solid option when you’re on the go and don’t have access to RO.
Icelandic: Yes, but only if VOSS isn’t available. I wouldn’t rely on it long-term due to potential BPA concerns.
Aquasana shower filter: Yes, especially for apartment living. It doesn’t remove everything, but cutting dissolved solids by ~58% makes a noticeable difference for skin and hair.
Aquasana Under-Sink Claryum Direct Connect: No. In my testing, it showed no difference. Not worth the investment.
Under-the-Sink RO (full system): Yes, if you own a home. This is the most comprehensive solution, delivering purified water to both the kitchen and bathroom. It’s less convenient for apartments due to plumbing restrictions, but unbeatable for whole-home coverage.