Hi guys,

How do you store and treat drinking water in order to be safe for use?

I have a village-source that is clean, cool, chlorinated, safe to drink, but the pressure is quite low and a few times during a year there's an outage.

Based on the above, I installed a small non-pressurized tank of 650L to bridge these outages and to improve pressure via automatic pump (DAB Divertron).

The tank is located in the basement, where the ambient temperature is 14°C normally, 23° in the hotest week of summer.

Already added submerged UV lamp to the tank (45W with 1/4 duty cycle), but I'd like to know what else I should consider.

What worked for you?

I have quite successfully "stored" 1200 litres of water in a plastic Eco tank over a period of nearly three years, by continuously using a small amount of water from the tank and replenishing the used water with fresh water from the municipal supply. I connected the tank through a pressure pump to our kitchen tap, an RO filter, and to the washing machine, in total using approximately 20-40l of water per day. This small amount of municipal chlorinated replacement water has managed to keep the total 1200 litres in the tank clean/fresh enough to use for washing dishes and clothes, and after filtration through the RO filter for all our drinking and cooking water. The rest of the house is still fed directly from the municipal supply. Over this period we have had a number of "water sheddings" lasting from hours to 3-4 days, and during those periods the stored water in this tank was used to also supply water to the bathrooms and geyser, and to flush the toilets. I'm happy to state that we survived even the longest of these shutdowns with water to spare.

Although the stored water is still quite clear, and odor free, the bottom of the tank has accumulated a thin layer of sediment deposited by our rather muddy municipal water, and I would not classify it as fit for drinking without filtration The RO filter really does an excellent job of filtering this water and not only making it fit for human consumption, but also for making exceptionally tasty coffee and tea - the only down side being that one wastes about 75% of the water that's filtered.

Hope this is of some use 😊

Edited July 9, 20251 yr by HennieL
Typo corrected

My experience (over a lesser time period) is similar to @HennieL 's and in line with what accquaintances report. Just keep the contents of the tank turning over (so to speak) and the water stays fresh. Most folks that I speak to draw from the tank on weekends, but I tend to switch over on the days the washing machine is in use. I have a 2.5 kl tank. There is a filter between the tank and the municipal supply to trap, but it won't trap bacteria.

16 hours ago, Youda said:

How do you store and treat drinking water in order to be safe for use?

In SA we are experiencing infrastructure failure due to lack of maintenance. When we move to the Western Cape a few years ago me and my wife( micro biologist) decided to install a 3 stage under counter RO filter to the kitchen faucet just to be on the safe side. My wifes recommendations was to also add a flow through uv sterilizer. I opted for the Aqua Topone YS series uv sterilizer with flow sensor supplied by Puritech.

16 hours ago, Youda said:

Already added submerged UV lamp to the tank (45W with 1/4 duty cycle), but I'd like to know what else I should consider.

Your submerged UV lamp with a 25% duty cycle (on ~6 hours/day) does help reduce microbial growth in the tank. However:

Submerged UV only disinfects near the bulb and doesn't treat all stagnant water effectively.

Consider switching to or adding a flow-through UV sterilizer after the pump, so that all water going to taps is treated.

Edited July 10, 20251 yr by TaliaB
3stage RO filter not 4 stage

26 minutes ago, TaliaB said:

Your submerged UV lamp with a 25% duty cycle (on ~6 hours/day) does help reduce microbial growth in the tank. However:

Submerged UV only disinfects near the bulb and doesn't treat all stagnant water effectively.

Consider switching to or adding a flow-through UV sterilizer after the pump, so that all water going to taps is treated.

And of course to have all this working reliably, you need reliable electricity. Which is why this forum is here.

Hi guys, thanks for all the feedback!

• I spend around 100L per day, so after a week or so the contents of the tank are refreshed

• Flow-thru UV sounds like a great addition

• RO would be great, as it's essentially a silver bullet, but I'd like to keep this as a method of last resort because of implications;

  • need to replace RO membrane frequently

  • produces quite a lot of "brine" when compared to yield

  • watter stripped of all the minerals is not the best for long-time drinking

BTW: This is current submerged UV cycle that I've set up, 6hrs total per day. Consumes around 8kWh per month, which is nothing:

Q: If you have an RO, how often do you change the membrane?

Q: If you have a tank, where do you have it located and what is the ambient temperature of surrounding air?

2 hours ago, Youda said:

• • watter stripped of all the minerals is not the best for long-time drinking

Add about 1/2 teaspoon of Sea Salt or Himalayan or Rock salt per Litre, adjust to your taste buds (i.m.o. it improves the taste and feel) and you will have more minerals than tap water.

Also you can get RO systems which include mineralization cartridges and even stand alone ' mineralization filters' .

3 hours ago, Youda said:

If you have an RO, how often do you change the membrane?

2 to 5 years is the normal replacement interval. In ideal conditions (good pre-filtration, low TDS(total dissolve solids)(feed water, regular use), closer to 5 years. In harsher conditions (high TDS, poor pre-filter maintenance, low water usage), 2–3 years.

6 hours ago, Youda said:

Q: If you have an RO, how often do you change the membrane?

Agreed with @TaliaB .

The secret to a long RO membrane life is to:

• Regularly replace the sediment pre-filters

• Most importantly, regularly replace the activated carbon pre-filter. This removes the chlorine in the water (chlorine actively damages the membrane and can ruin a membrane in a very short time - days, not months, if present in the water in measurable quantities).

• Ideally the membrane holder should also be flushed with "bypass" flow to actively flush away any mud/sediment that accumulates in this housing and around the membrane. It's normally a good idea to flush the membrane at least twice during the interval between replacement of the pre-filters.

I would not fret about the "good elements" stripped from the water by the RO - I have been using RO water for many years, with no detrimental effect, but the post filtration mineralization cartridge does improve the taste of the water.

7 hours ago, Youda said:

Q: If you have an RO, how often do you change the membrane?

TDS meters are cheap, measure the feed and purified water to check effectiveness.

There are other methods of keeping your long term water storage clean obviously a multi stage filtration system helps to make the water safe for drinking however it does not remove pathogens bacteria and viruses.

Inline UV filters work well enough RO systems with UV are the most effective however the problem is that the RO process removes all the natural minerals from the water and is actually bad for human consumption if minerals are not reintroduced into the water and these systems can consume a bit of power and they cost a bit of money.

One very safe and relatively inexpensive method I personally use in my system being off grid and my only sources of water are rainwater and borehole water is the following.

4 stage filter for drinking water but I treat my water with hydrogen peroxide the ration is very small you only need 1 PPM to 0.5 PPM peroxide in your water and this kill bacteria pathogens and viruses.

I douse the water on a set schedule and test the peroxide content from time to time to ensure the ratio is within acceptable levels I plan to add a UV filter into the system at a later stage the combination of the UV and Peroxide will ensure that all biocontamination is eliminated from the water The UV instantly kills and the peroxide prevents new infection post UV filtration the peroxide does naturally break down so if you are storing water long term then you would have a schedule of dosing and UV circulation this will maintain the water quality and prevent biocontamination.

In my case I use the water continuously so I follow a schedule the cost of peroxide is very low and you use very little in a cycle in my case less than 500 ML 50% Peroxide in a year at a cost of R120 Per litre if you buy bulk then the cost goes down to R48 per litre.

The upside is that it does not alter the taste of the water in any way.

I later plan to add a automatic dosing system for the peroxide based on the measured ratio in the water to keep it between 0.5 and 1 PPM

I had my borehole water tested and its very clean at below 150 PPM in minerals with no heavy metals or chemical contamination in the water not even fluoride and it has a nice neutral PH of 7.3 so for drinking water its great for plants I have to lower the PH a little but that's where my rainwater system comes into play this lowers the PH to around 6 to 6.5 so then I have to make very few adjustments to the PH and the rainwater is exclusively for plants those tanks I top up in winter with borehole water.

I also use the Peroxide for growing plants etc has many beneficial uses.

RO Systems are great if you have very contaminated water that has high mineral and heavy metal contamination in it but if your water is already reasonable quality then RO is overkill and expensive besides the power requirement if you need to treat larger volumes of water to make it drinkable or safe to use on plants high salinity will affect plant growth unless you are growing salt tolerant plants.

In my case I am off grid so power consumption is a consideration for a system.

Hi all. There is talk here about sludge build up in tanks and filters that can prevent or reduce that build up.

I currently have a filter in the line that fills my tank from municipal water. I have asked the plumber to confirm the number of microns. It certainly captures the coarse grit that we sometimes get in municipal lines. But what rating or gauge or whatever of filter do I need to mitigate against sludge build up?

I am thinking that I need two filters. The first (IE closest to source) to capture the rough stuff, the second (between first filter and the tank) to capture finer sediment.

Edited July 18, 20251 yr by Bobster.
Sppeling

Also planning a 2,5kl tank as a buffer for all my water requirements. i.e. the house will be served via a pressure pump from the tank.
Something I am considering is a typical pool sand filter before the municipal water enters the tank.
My question to those that have installed tanks. Would the sand filter prevent any sediment build up in the storage tank and also would the additional costs really be worth the extra cost.

On 2025/07/18 at 10:23 AM, Bobster. said:

But what rating or gauge or whatever of filter do I need to mitigate against sludge build up?

I am thinking that I need two filters. The first (IE closest to source) to capture the rough stuff, the second (between first filter and the tank) to capture finer sediment.

I use three pre-filters on my RO. Closest to the raw water input is a 10 micron sediment filter, then an activated carbon block filter to remove the municipal chlorine (not needed if you use borehole or rain water only...) and closest to the RO membrane a 1 micron sediment filter, to remove smaller than ten micron sediment and also the fine black powder from a freshly installed carbon block.

1 hour ago, HennieL said:

I use three pre-filters on my RO. Closest to the raw water input is a 10 micron sediment filter, then an activated carbon block filter to remove the municipal chlorine (not needed if you use borehole or rain water only...) and closest to the RO membrane a 1 micron sediment filter, to remove smaller than ten micron sediment and also the fine black powder from a freshly installed carbon block.

OK. So my filter turns out be a 130 micron disc filter. Really only good for keeping boulders out. But doesn't it take some pressure to get water through a 1 micron filter?

I see now on re-reading your previous post that you want to filter water going into your tank. My previous answer assumed that you wanted to filter the water going to a RO filter with small pressure tank... Could you please clarify?

My RO system has a small built in pressure boosting pump that makes it easier to force the water through the pre-filters, and especially through the membrane, but municipal water pressure also works - just slower. If this is meant to filter water used to fill a large storage tank you would obviously not use a RO membrane in your filter setup - that would be very, very slow indeed.

6 minutes ago, HennieL said:

I see now on re-reading your previous post that you want to filter water going into your tank. My previous answer assumed that you wanted to filter the water going to a RO filter with small pressure tank... Could you please clarify?

Sure. I am wanting to prevent a sludge build up in the tank, and that needs a filter between the municipal supply and the inlet in to the tank.

The question is, what is creating the sludge.

• Is it just the impurities and debris?

• Product of bacteria and other organisms?

• Product of elements that are naturally dissolved in the water itself, like Ca, Mg, Fe atc?

I would go for the LAB analysis of the sludge sample first, before spending too much money on something that will not solve the root cause of the problem.🤔

4 hours ago, Bobster. said:

Sure. I am wanting to prevent a sludge build up in the tank, and that needs a filter between the municipal supply and the inlet in to the tank.

Understood - then just the two sediment filters would be fine - and perhaps only use a 10 micron and a 5 micron filter to just reduce any sludge build up. You should also make sure that the "manhole" lid is screwed down very well, and install a "snorkel" with an air filter to prevent dust from entering the water from the air.

13 hours ago, Youda said:

The question is, what is creating the sludge.

IDK. There was some talk on this thread about sediment in tanks so I thought it would be a good idea to mitigate against that. Though by now my geysers would be knee deep in the stuff.

On 2025/07/09 at 6:01 PM, Youda said:

Hi guys,

How do you store and treat drinking water in order to be safe for use?

I have a village-source that is clean, cool, chlorinated, safe to drink, but the pressure is quite low and a few times during a year there's an outage.

Based on the above, I installed a small non-pressurized tank of 650L to bridge these outages and to improve pressure via automatic pump (DAB Divertron).

The tank is located in the basement, where the ambient temperature is 14°C normally, 23° in the hotest week of summer.

Already added submerged UV lamp to the tank (45W with 1/4 duty cycle), but I'd like to know what else I should consider.

What worked for you?

Are there any light spots on your basement? Windows? The darker the place the better for water. Light will create more trouble than temperature regarding microorganisms growth.