What's a cistern?

 

By: Chris Hanley

A cistern is a man-made reservoir or receptacle for holding water. It provides, in many cases, the sole water supply for properties on St. Croix. City water service does not extend far beyond the town limits, therefore cisterns are a very important part of any structure. Most cisterns are located where one might normally expect to find a basement. Think of it as a very flooded basement! It is filled by rain collected from the roof through downspouts, which lead into the cistern. It is most commonly made of concrete and a part of the overall structure, although you may find stone or pre-made tanks as well. Many cisterns are "sealed" with a paint-like latex rubbery material.

It does a perfect job of sealing any potential seepage areas or just for a clean, smooth, surface. One good coat will probably outlast you. To provide access to the cistern, most have a square 2'X 2' lift-able cap to allow for entry to clean & maintain. There are also overflow outlets usually of 6" PVS/iron located at the top of the cistern sticking out the side of the structure. It is a good idea to keep these outlets covered with a screen cap to prevent the entry of any number of god's creatures, but still allow water to flow out. You don't have to worry about algae in a properly sealed cistern, even without chlorination. That's because without sunlight, algae cannot live. Many people occasionally add a bit of bleach anyway.

HOW DOES THE WATER GET TO MY FAUCET?

Somewhere on the property there is a water pump and pressure tank. Often you will also find the water heater in the same place. The pump is connected to a suction pipe, which extends from the top of the cistern down to within a few inches of the bottom. This gap prevents any potential sediment from getting sucked up into the system. Some suction pipes have a special fitting on the end, which assists with this. The pump sucks the water out of the cistern and into your building, pressurizing the pipes within the building. When you open an outlet (faucet/toilet flush etc.) the pressure in the system slowly drops until a pressure switch on the water pump kicks on the pump to re-pressurize the system. You may often hear the pump come on as you use water. In recent years some people have chosen to install in-line filter systems which further clarify the water. These islands are blessed with nice clean air, and the natural purification by distillation courtesy of Mother Nature is commonly considered good enough!

WHAT DO I DO WHEN IT DOESN'T RAIN?

Sometimes rain no come. Not to panic... it just means you have to get out the checkbook to get some delivered. There are many water delivery services on the island. The rates are usually around $85-95 for 3000 gallons of well water ($150/3000 gal. distilled) delivered and pumped into your cistern. Most often it will be sent through the overflow, but in many of the newer homes, fill pipes are purposely installed near the driveway or other convenient location to ease the chore of the delivery person. So long as you don't waste water, you should rarely have to buy it. Some areas of the island get more rain than others.

HOW MUCH WATER DOES MY CISTERN HOLD?

Cisterns vary in size from house to house. Generally you should expect to have 10 gallons of storage capacity for every square foot of roof area. Check the latest local code for the exact requirements. Thus, 2000 square feet of roof requires 20,000 gallons of cistern capacity. Remember to include the overhangs, etc.. A quick and easy way to figure out how big a cistern is, is by measuring it; (length X width X height) = cubic feet X 7.4 = # gallons. In most cases people will offer estimations of size. Rarely does a person know the exact size of his/her cistern. Even on most real estate listings, you will see an approximate size... this is common.

DO I NEED TO CLEAN MY CISTERN?

That depends on whether or not it is dirty! It is generally recommended that you clean your cistern every 3-5 years. But that really depends on how much debris gets into it. If your house is surrounded by leave-dropping trees or there's a storm blowing dirt and particles around or your don't have proper screen covers on your gutters or ... or ..., etc. A quick visual check with a flashlight will reveal how much dirt has settled on the bottom. It is normal to have accumulations of dirt and sediment on the cistern bottom. But be sure that it isn't thick enough to dose the gap between the bottom and the suction pipe leading to the pump. If this happens then you will soon be seeing dirty water coming into the plumbing system. You do not want this to happen. Many people opt for cleaning the cistern themselves. It is not an easy or pleasant job to do. In most cases you are better off calling a reputable cistern cleaning company. It is usually cheaper and easier to let an expert take care of it for you.

THERE'S A FROG IN MY CISTERN, WHAT DO I DO?

Don't panic Believe it or not, this is VERY common. Don't try "bleaching" or "salting" him out, you'll only spoil your water supply. Instead, have your cistern cleaned and checked for the spot where the frog got in. There is definitely a gap, opening or other small crevice where god's creature has found his way in. They most commonly enter through the overflow pipes, which may not have a screen cap or cover. Many people consider this to be normal and acceptable, and do nothing about it. We recommend you have it cleaned. Once the cistern is cleaned, make sure that this entry area is promptly closed off.

 

For any of your real estate needs ... remember to call Farchette & Hanley Real Estate, 
and ask for one of our full time, professional brokers;

Chris Hanley

Rick Rothenberger

Jan Hanley

Lad Concepcion

David Fedeles

Dave Carr

Jack Capiello

 

 

Farchette & Hanley Real Estate Since 1930

# 52 King Street, Christiansted, St. Croix, VI 00820

(800)964-9755 or (340) 773-4665