Some engineer friends and I like this one given how modular it is:

https://www.theperfectwater.com/reverse-osmosis https://www.youtube.com/watch?v=9RqoPpZbszY

In particular the permeate pump makes it more usable and less prone to clogging and the 'insta-hot' option is great for tea/coffee. I'm not a fan of their branding and vague NSF certifications but likewise see fewer red flags with them than their competitors. Eg it's made in the USA, they've been around for a while, they have a few patents to their name, and their based out of Phoenix where the water tastes like garbage so they probably dog food their product.

My only wish is to upgrade the remineralization process to 'set and forget' a profile as described in this post on how to DIY name brand mineral waters: https://khymos.org/2012/01/04/mineral-waters-a-la-carte/

For something less daunting and ready to go I've heard good things about the Waterdrop G3 P800 RO System but they do have an affiliate system so who knows how trustworthy they are: https://www.ro-system.org/waterdrop-g3-p800-review/

> not sure that it filters some of the PFOS/PFAS chemicals

Just to clarify the terminology: PFOA, PFOS, PTFE, and thousands of other chemicals are all examples that are part of a larger group of (mostly) problematic chemicals called PFAS.

Here is the EPA’s guidance on filtration standards and how to identify filters that are effective for PFAS: https://www.epa.gov/system/files/documents/2024-04/water-fil...

That PDF has links to products certified by various certification bodies, and suggests looking for products certified against NSF 53, NSF 58, or both. but the EPA also notes the following:

> It's important to note that the current certification standards for PFAS filters (as of April 2024) do not yet indicate that a filter will remove PFAS down to the levels EPA has now set for a drinking water standard. EPA is working with standard-setting bodies to update their filter certifications to match EPA’s new requirements. In the meantime, remember that reducing levels of PFAS in your water is an effective way to limit your exposure.

EWG has a list of recommended filters: https://www.ewg.org/research/getting-forever-chemicals-out-d...

I use Coway, a Korean brand for my water filtration needs. They are a good brand and actually certified but looking closely at the product manual, they do not make the claim that they filter PFAS (defined as having a fully fluoridated methyl or methylene group): indeed they only claim to filter several chlorinated substances including tetrachloroethene.

I'm also curious about this - particularly about filter membrane materials and nanoplastics

Make sure you have good air filtration too.

I have built and sold RO systems for 20+ years. It's a weird industry and there are some competing desires in place. In general it's kind of a mess and it's difficult for consumers to navigate.

You can build your own system for less than $150 from cheap parts on ebay. You can buy a branded unit at a big box or amazon for $150-250. Or a "health" branded version for $300-800. Or have an installer put whatever they sell in for $500-1500.

My experience is that you will get nearly identical water quality from each of those systems. There are different options and some fine details but the fundamentals haven't changed in decades and you are paying for some collection of service, parts quality, future replacement costs, marketing and snake oil.

NSF certification is good, it will rule out products that are flat out harmful. I have seen lots of cheap filters with fake certifications and there are many great filters that it don't carry certification. NSF material and safety cert (51) is a good one to look for, beyond that is has more to do with how the product will be sold and marketed than a real measure of performance.

$250-500 is probably the right price range for a diy install unit. Check for replacement part costs, buy something with standard components and cartridge sizes. Learn how it works, change the filters on time and expect to replace components every now and then.

The RO industry is such a snake oil mess that instead I went for a high quality activated charcoal filter that can easily be changed after half a year for 30$, and combine it with water distillation.