I think The zerowater is slightly acidic is coz it is too low in TDS due to the ion exchange resin (maciam like RO). So low TDS would just very easily get acidic due to absorption of CO2 in the air. Same goes for RO perhaps.
You can test for this effect with pH test liquids, test immediately after filtration and then 2-3hrs after filtration while left standing ard.
"Normal" filtered water here are usually slightly alkaline, due to a wee bit of dissolved bicarbonates and stuff which acts as a buffer.
RO and nanofiltration are the technologies that have waste water discharged to prevent membrane fouling. Some Ultrafiltration also have this, to prolong the hollow membrane lifespan, but i think SG water no issue lah, not many particulates here.
IMO, a constantly pressurized undersink system i think is a bit risky in terms of flood risk, but that's just me.
I have experience with those PE plastic quick connects due to my 12V pump for Aircon cleaning, well lets just say that if you were to expect them to stay connected leak and problem free for years, i think that's a bit asking for too much esp with the huge number of connections there.
You might want to modify a bit, earlier in the thread i have links to Taobao tap diverters and 2分 hoses. So basically it's like those on tap faucet filters, you want filtered water then you switch and divert the water to the filter.
For undersink/on-sink/whatever filtration, i'd recommend the DIY 10-inch canisters.
This is a very good cartridge, simple all in one. But i think not many people need that kind of high reduction of fluoride and chloramine. It also reduces lead and many other stuff.
6 mths or 500 galloons. Probably you'd hit 6 months. If you do boil the filtered water before putting into a hug/pot for serving, then you probably can push till 9-12 mths (coz any bacteria which set up camp in the charcoal would have been killed).
https://www.amazon.com/gp/product/B00AOKJDLI/ref=ox_sc_sfl_title_5?ie=UTF8&psc=1&smid=ATVPDKIKX0DER
It has catalytic activated carbon (not the normal activated carbon) which is like say 10 times more effective + 10 times longer lifespan than normal activated in adsorbing CHLORAMINES. We practically don't have chlorine issue at the end-user end, that is very easily dealt with by normal activated carbon with crazy lifespan/capacity of the activated carbon, and besides the absolute chlorine levels when it reaches out tap is probably say 0.25ppm coz that's how it works due to its high reactivity and disinfection properties (PUB uses 2.5ppm average at water works). Chloramine has less disinfection properties (secondary disinfectant) but has much higher persistence in our pipes.
Someone rearing shrimps recently just said that it needs 5 days to have let the chloramines outgas naturally? I don't know, nowadays i don't keep fishes already. I guess 2 or 3 foot tank partial water change still can tahan 5 days worth of standing water around the house? Try that for drinking water, bacteria all multiply and set up playground liao.
Some terms that you'd come across once you start to research :
Total chlorine = Chloramine + chlorine
Free chlorine = chlorine
How they determine chloramine levels is Total chlorine - Free chlorine.
There are also quite a couple of good solid carbon block filters on Amazon. See if you are interested in lead reduction etc. Go for the 0.5 micron ones, good performance.
Solid carbon blocks is just a name, from what i managed to search.....the Taobao ones are cheap but still not there in terms of performance (you get what you pay for).
You might want to get a cheap 1 micron PP sediment filter 10-inch filter and use that as pre-filter before the more expensive Amazon filter.
I don't think we have use for Ultrafiltration with tap water (pore size ranges from 0.01 - 0.1 microns). The 1 micron PP filter is really sufficient for sediment particulates.
Anyway, Amazon now has CITISG promotion code till this Saturday morning (Friday USA time), usd 15 promo code deduction.
3M Filtrete Maximum filter is a 0.5 micron solid carbon block (not catalytic activated carbon) which reduces lead, and is at a cheap usd 23.99.
However only 3pcs max per customer, so you gotta add in other eligible stuff to hit usd 125 for free ship.
The good thing is that you can use this piece of filter and incorporate together with other DIY 10-inch canisters, no issue....just need a bit more space.
https://www.amazon.com/gp/product/B01L0ADH3K/ref=ox_sc_act_title_2?smid=ATVPDKIKX0DER&psc=1
Note that it uses 3/8 inch 3 分 hoses. So you'd need to get some 3分-> 2分 adapters, those TB sellers selling the accessories like tap diverters all would have. I posted before 1 seller earlier.