High salinity water

if tap water is 1.5 ms/cm n im under the assumption that its filtered seawater therefore high salinity, will soil plants suffer or is this still safe levels?
is there anything i can do to remedy this?
Also is there a way i can sort of find out how much or at least the range of NaCl in this water without having it get tested or asking the source (no reply)?

You could get an reverse osmosis system for your home if you feel this is a problem.

If it were me, I would not worry about watering plants unless I saw the plants having problems.  The soil might possibly filter that out.

I know of no way of knowing without a water test.

1.5 mS/cm translates to 1500 µS/cm.  (Also, 1.5 mS/cm = 1.5 dS/m.)

1.5 mS/cm translates (very approximately) to 855 mg/L, which is the unit of salinity found in many agricultural charts. If my math is correct, your water is slightly, but not nearly as saline as seawater. As far as I can tell from different sources, it's roughly in the middle of the low-to-moderate risk range.

It appears your water is at the high end of potable water that is acceptable in the US. This site discusses typical conductivity ranges:
https://atlas-scientific.com/blog/water-conductivity-range/

My understanding is that conductivity and total dissolved solids (TDS) are only rough guides though. The actual effect on plants depends on the types and percentages of ions (especially sodium) present. A water test will provide a breakdown of this chemistry.

This is an excellent article discussing all the chemistry variables and the types of plants tolerant of certain salinity levels:
https://www.agric.wa.gov.au/water-management/water-salinity-and-plant-irrigation

This source has a chart showing maximums for garden plants (units are dS/m):
https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=1042&context=extension_histall

Hope this helps.

Douglas,
Awesome comment!

Jiemsi,
Basically I think the main concern is ensuring that the salt gets flushed out of the soil, at least periodically, (especially in the plant’s root zone), so that salt does not accumulate too much in the soil.

It’s a case of conservation of mass. The mass of salt that remains in the soil will be the mass of salt going in minus the mass of salt going out. Thus it is essential that, at least periodically, some of the water flow completely through the root zone.

I suppose this requires at least 2 things:
1) good drainage. Loose soil, no compacted layers. If there is a hard-pan layer then an initial deep plowing is probably necessary.

A percolation test may help determine drainage. Dig a hole. Add water. Measure how fast it drains.

2). Periodic flushing, nearly to the point of flooding the soil (with rain or irrigation water) at certain intervals may be needed long-term.

Wikipedia suggests “The primary method of controlling soil salinity is to permit 10–20% of the irrigation water to leach the soil, so that it will be drained and discharged through an appropriate drainage system. The salt concentration of the drainage water is normally 5 to 10 times higher than that of the irrigation water which means that salt export will more closely match the salt import and it will not accumulate.”

https://en.m.wikipedia.org/wiki/Soil_salinity_control

If the above isn’t possible, consider harvesting rainwater instead.

Also follow soil health principles.

1) “Armor on the soil” Mulch cover.
2) minimize soil disturbance (after initial earthworks)
3) diversify plants
4) keep a living root (no fallow period)
5) livestock integration

It’s a complex topic, I’m sure there’s a lot to learn about it.

As far as measuring the NaCl concentration in your water by yourself, I think it isn’t so easy.  

Although…I had a wild idea that might work…

I’m imagining taking a measured volume of water, boiling it down somewhat.  Taking a small sample of that concentrated water. Measure its EC. Then, using a gram scale, add a small but measurable amount of the salt of interest (NaCl), (and perhaps other salts as well).  Stir. Measure the EC again. Use the difference in EC values to estimate the slope of the EC vs. concentration curve for that salt component. Continue boiling down and repeat the same measurement procedure at different concentrations.

With this data I’m guessing it might be possible to estimate the original NaCl concentration.

If this makes any sense, let me know and maybe the idea could be developed further. Otherwise, ignore it or consider purchasing a proper water test.  

Poking around the Web, I see a number of home testing kits for sodium that are a fraction of the cost of a lab test.