Experimenting with Tap Water for Opae’ula Tanks

Buying cases of bottled water for the brackish water mix in my small tanks has been such a hassle that I’m taking a serious look at tap water. Dennis Nakashima uses tap water, apparently without any problems.

My nephew, a hydraulic engineer with a private firm, has worked with the Honolulu Board of Water Supply on a number of occasions and is familiar with our water quality. He says that the BWS does add chlorine to our tap water in Honolulu to control bacteria — but not chloramine. This is good news because chlorine gas can be removed easily but chloramine is a different story.

Other parts of Oahu and Neighbor Islands may rely on different chemicals, so it’s best to check. My nephew provided further information:

Click on the link below to get the water quality report for you property:


Once you get to the website click on:

Search for and download the 2016 Water Quality Report for your address

Type in your street address (no need to include “Street”).

I’ve read that leaving water out in an open container overnight will remove chlorine gas. There are other natural methods, including leaving the open container in direct sunlight, swishing the water around with your hand, pouring from a higher distance. I could boil the water, but that seems inefficient. I could purchase a water filtering system, but that seems expensive when maintenance is factored in. Mechanically, I could run an airline from a pump into the water to speed up the dechlorination. I could also add chemicals, including vitamin-C, but I don’t want to take the risks involved.

Leaving the water out overnight in a 3-to-4 gallon open tub seemed to be the easiest, most natural, and least risky method. I then poured the water into empty plastic water bottles for storage.

In this process, it’s important to remember to be very careful when using buckets, bottles, funnels, etc. that have been washed with soap. Be sure to rinse thoroughly to completely remove all residue.

The Water Cycle,” Board of Water Supply.

I also realize that tap water could contain other natural chemicals that might impact water quality. However, Honolulu’s water supply seems to be very clean:

Most of Honolulu’s consumers get their fresh water from the island’s extensive aquifer systems…. Aquifers are permeable rock formations from which fresh water can be drawn. In some cases … some of the wells are artesian which means … this water … has taken hundreds or millions of years to filter down to the aquifer rock.1

Thus, I’m hoping that our island’s natural filtering system has removed most if not all the potentially harmful chemicals.

The Water Cycle,” Board of Water Supply.

There’s also the possibility that the plastic containers that I’m using might somehow add chemicals to the water. I need more info about this.

This morning, I topped off the 18- and 1-gallon tanks with the dechlorinated tap water. I’ll continue using bottled water for the 10- and 1.5-gallon tanks. If this experiment proves successful, I’ll switch completely to cleaned tap water.

1 Larry Kobayashi, “What Is the Current State of Fresh Water Supplies in Honolulu and Oahu: Will We Have Enough Water for the Future?” Hawaii First Water, LLC, 12 Sep. 2014.

This entry was posted in Uncategorized. Bookmark the permalink.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s