Find answers to your questions about Rainley's high-quality shower products. The MicronFlo filter cartridge lasts up to 10,000 gallons under EPA-defined moderate contaminant conditions. But water is not the same everywhere, and the differences directly affect how long a cartridge lasts.

If your home is on municipal water i.e. your water has been treated by your local utility, but that treatment varies by city or town. Much of that variation comes down to geography where a utility's water originates (surface reservoirs versus underground aquifers), the mineral composition of the local soil and bedrock, and the distance water travels from source to treatment plant all shape how it's treated and what's in it. Some utilities use chlorine for disinfection, others use chloramine, which holds up better over distribution distances. Municipal water also carries different levels of hardness (calcium & magnesium) depending on the source your utility draws from, and different levels of sediment and total dissolved solids (TDS).

If your home is on well water, your water has not gone through municipal treatment at all. Well water often carries higher sediment, higher mineral content, and in some regions, additional issues such as iron or sulfur (hydrogen sulfide), which causes a rotten egg odor, often also tied to the local geology the well draws from. Well water can place a heavier load on your filter cartridge than municipal water does.

Because of these differences between municipal and well water, hard and soft water, and chlorine and chloramine treatment, a household in California, a household in Texas, and a household in Florida can each exhaust the same cartridge at a different rate, even using the exact same number of gallons. Household size and shower habits add another layer of variation on top of that.

Why is the MicronFlo cartridge transparent?

Most shower filter brands tell you to replace your cartridge every 90 days, or ship you a new one on a fixed schedule. Their cartridges are opaque, so you can't see inside, and there's no way to tell whether the filter is still working or was used up weeks ago. A date on the calendar is the only guidance they can offer.

We think that gets it backwards. As explained above, two homes can run the same number of gallons through a cartridge and wear it out at very different rates, depending on their water source, hardness, treatment and household size. On a fixed schedule, some people throw away a cartridge with life left in it, while others keep showering through one that stopped doing its job long ago.

So we made MicronFlo transparent. As the pleats capture sediment, rust and other particles, they change from white to amber, brown or grey depending on your water, and in some homes the change is only slight. Every time you open the housing, you can see what your water is actually leaving behind, and decide for yourself when it's time for a new one. Other signs help too: the chlorine smell coming back, your skin and hair feeling less soft, or the flow slowing down.

MicronFlo is rated for up to 10,000 gallons under EPA-defined moderate contaminant conditions. Treat that as an upper limit, not a countdown. Your water sets the real number, and your cartridge shows it to you.

Replace by evidence. Not schedule.

What is a TDS meter, and do you need one?

A TDS meter is a small handheld tester that measures total dissolved solids: the minerals and salts dissolved in your water, such as calcium, magnesium and sodium. It works by measuring how easily the water conducts electricity, and it shows the result in parts per million (ppm).

It's a handy rough gauge of how mineral-heavy your water is. But it can't tell you what those dissolved solids actually are, and it doesn't pick up many of the things people most want out of their shower water: chlorine, chloramine, trace heavy metals, sediment particles, microplastics or bacteria.

That's why a TDS meter isn't a good way to judge any shower filter, ours included. Shower filters like Bossa are built to reduce chlorine, chloramines, heavy metals and sediment, not to remove dissolved minerals. So the TDS reading before and after the filter will look about the same, even when the filter is working well. If you see a video using a TDS meter to "prove" a shower filter works or doesn't, the number isn't measuring what the filter does.

So no, you don't need one. Better ways to understand your water:

• On city water: look up your utility's annual water quality report (the Consumer Confidence Report), usually on its website.
• On well water: a certified lab test tells you what's actually in it.
• To check chlorine: inexpensive chlorine test strips, used before and after the filter, show whether it's being reduced.
• Every day: your MicronFlo cartridge shows you what your water leaves behind each time you open the housing.

Enjoy free ground shipping on all orders within the continental US. Currently shipping within the US, we process orders quickly and cannot edit or cancel once placed. Once you know how fast your household uses a cartridge, you can subscribe and choose your own delivery interval, every 2, 3, 4 or 5 months, with the best pricing and early access to product launches. Rainley products, including Bossa inline filters, and MicronFlo cartridges, are BPA-free and compatible with ½" IPS connections, the standard for US shower setups.