Too low pH after RO

[David22]

I live in the country where (primary)standard for pH for drinking water is 6,5 to 8,5. And there is no separate standard for "purified water". Tap water(municipal)pH is about 6,7. Standard residential RO system (sediment 5u, GAC, Carbon Block, TFC membrane, carbon postfilter) lower pH to 6,2 sometimes below 6. And that's against the law!

Is there any type of pre(or post) filter which can make RO permeate water pH > 6,5 (in standard) but keeping TDS low?

Thanks.

 

[vintage70]

limestone treatment will maintain 6.7 and not increase TDS

 

[Chris73]

Sorry, could you please spell out: RO system and TDS? That may help to understand your needs!

 

[David22]

RO: Reverse Osmosis
TDS: Total Disolved Solids

 

[feather]

The low pH is expected with CO2 passing the membrane; with low conductivity water the pH depression could be more significant. Chris73 has the answer for you.

 

[feather]

My error. I meant Vintage70, not Chris73.

 

[Rumays]

The standards for pH increase in the RO industry in post treatment are:
1] Caustic (NaOH)
2] Sodium Bicarbonate
3] Soda Ash
4] Chemical Lime (quicklime)
5] Hydrated Lime