Actual Measurement of Water Flow Impact by 20" Big White Bottle for Whole House Water Purification
Which one to choose? How much does it affect the water flow?
I conducted a simple test.
Abandoning the Pre-filter
Previously, to remove particles from the water, I installed a pre-filter and used it for over two years, but it turned out to be completely useless: backwashing didn’t yield much, and the filter screen appeared clean upon inspection. I live in an old apartment building with a water tank, which might be specific to the Shanghai area.
Hardly any backwashing occurs
The only purpose of the pre-filter’s 40um precision is to filter out sand and silt. I chose to install filter cotton directly instead. Additionally, to install a water softener, residual chlorine needs to be removed for it to have a long service life, so an activated carbon filter element is also required.
Big Blue Bottle? Big White Bottle?
I looked into both the Big Blue Bottle and the Big White Bottle. The Big Blue Bottle is for non-retail industrial use and has weaker explosion-proof capabilities compared to the white bottle, thus requiring a bunch of accessories. The Big White Bottle, on the other hand, solves everything directly. The price isn’t much different from a linked setup of blue bottles. At this point, there’s no need to overthink it—less is more.
In the end, I directly ordered from an authorized offline store: a BFW-20" Big White Bottle + RFC20BB composite filter element, with 10um precision. The price was 1600 including installation, and it came with official WeChat-verifiable anti-counterfeit labels. If you buy it online and install it yourself, you might get it for around 1300, but without the anti-counterfeit labels. There seem to be counterfeits online, while offline options are expensive. It’s hard to judge authenticity, and the manufacturer doesn’t seem to care much about online sales. Waiting for domestic alternatives to replace it in the future.
Actual Measurement of Water Flow Impact
Many people worry about affecting water flow and struggle with choosing the size, or whether to use a linked setup. Opinions online vary widely. Here, I provide my own actual measurement data. Water pressure doesn’t need testing because static water pressure remains largely unchanged regardless of how many devices you install. Therefore, water flow rate is the correct metric to test.
Test Environment:
- Pentair 20" Big White Bottle + RFC20BB composite filter element;
- Home water pipes are 6-fen DN25x4.2 S2.5; the inlet pipe is 1-inch;
- All four faucets in the house fully open: 4-fen soft pipe cold water faucets x2 (inner diameter 9mm), shower faucets x2 (inner diameter 16.4mm)
| 20" Big White Bottle Filtering | Direct Bypass | ||
|---|---|---|---|
| Statistical Values | Time / sec | 17 | 17 |
| All home faucets fully open, | Start Water Meter / m³ | 0.6286 | 0.6559 |
| Observe water meter readings under two conditions | End Water Meter / m³ | 0.6354 | 0.6635 |
| Total Flow / m³ | 0.0068 | 0.0076 | |
| Total Flow / L | 6.8 | 7.6 | |
| Unit Flow Rate | Flow m³/s | 0.000400 | 0.000447 |
| Flow m³/h | 1.440000 | 1.609412 | |
| Flow L/s | 0.400 | 0.447 | |
| Flow L/min | 24.000 | 26.824 | |
| Pipe Constants | ppr 6-fen inner diameter | 16.4 | 16.4 |
| Inner Diameter / m | 0.0164 | 0.0164 | |
| Cross-sectional Area / m² | 0.000211241 | 0.0002112 | |
| Calculated Flow Velocity | Velocity m/s | 1.894 | 2.116 |
The water flow velocity in my home is a bit slow, but as can be seen, the 20" Big White Bottle with the composite filter element reduces water flow by about 10%.
As for the 10" Big White Bottle, although official tests show the composite filter element flow rate for the 10" is directly halved, those tests are conducted at 0.06 bar. What would happen under typical household conditions of 2 bar?
248520b
