Wondering if you should use
Municipal, Well, Pond or Lake water for irrigation?
Based on our many years of experience with municipal, well, pond and lake water sources for irrigation, Aquarius Landscape Sprinklers offers following information to assist with your decision.
Municipal ("city") water
The best and cheapest source is municipal water because it is a clean and dependable supply with a known pressure. Well water is the second best and cheapest of all sources if it is of good quality and in plentiful supply. Drip systems need the cleanest water and are supplied with a fine-mesh disc filter. Lake or pond water, although “free,” have other implications.
Municipal water is the most predictable and usually needs no additional filtration. It is also chlorinated and prevents the buildup of bacterial slime in the valves (this usually takes a year to develop with pond or lake water sources and 2-4 years with well water).
Generally the pressure provided by municipal sources is relatively constant, with minor fluctuations depending on the time of day. As newly developed lands are converted to homes, area pressures may decline. Therefore irrigation systems installed in new neighborhoods should be designed conservatively to allow for future development.
Since municipal water prices are often tied to sewage disposal, having a second meter installed will avoid this dual pricing. Hidden costs to having a second meter include the year-round billing when the water is used for only 4-5 months. Large irrigation systems may have a “payback” period of 2-4 years whereas small residential systems may never achieve a “payback”. Municipal water must have a suitable backflow preventer installed to protect the municipal water supply from contamination.
Many wells have relatively clean water and remain trouble-free. However, there is always some grit, iron or other sediment mobilized from the well during irrigation usage, these contaminants may be easily removed by using a sediment filter.
The grit filter is cleaned merely by opening a valve and allowing the sediment to be flushed into a bucket. Depending on the grit, the nylon mesh screen can be removed and rinsed off in a bucket of water and then replaced. Some wells have more grit than normal and prevent ongoing filtration problems with irrigation systems.
Many people are concerned about the overuse of the well water for irrigation. Wells use a water source that is invisible and need to be monitored so that domestic water is not consumed at the expense of irrigation needs. By creative design techniques and using the automatic controller, conflicts with domestic usage can be eliminated or at worst, minimized.
The well casing and pressure tank provide upwards of 200 gallons of reserve water and as the irrigation system uses this water, it is also being refilled at the well recharge rate. Therefore, using 8 gallons per minute to irrigate, having a well that recharges at the rate of 4 gpm, will actually result in a draw down of available water of 4 gpm. This allows for 50 minutes of irrigation. Allowing the well to then recover for an hour will refill he well casing and pressure tank so that the same water is available for the next irrigation cycle. An automatic controller can be programmed for 3 or more short cycles in one day if needed. By using the well for irrigation at night (off peak), there will be sufficient time for the well to recover in time for normal domestic usage.
Initial costs to use well water are for the plumber to attach the filter and lead the water pipe to the outside of the house.
Ponds generally have a readily available supply of water. However there are many creatures that live in this water that can be sucked into the system causing a slime buildup inside the valves and sprinklers.
This slime can cause valves that fail to close completely – allowing them to leak. A good filtration system is important, as is a regular service schedule to clean valve diaphragms.
The additional concerns of maintaining a pump, intake valve, and priming a pump that is on shore make the pond water source a system that needs regular service.
Initial cost of the pump, tank, intake line and expanded filter system add extra cost to the irrigation system. As the water level changes in the pond, the foot valve intake may need to be extended – unless it is floating. As the summer progresses, pondweeds and algae may add additional water quality management issues.
Lake water tends to be cleaner than pond water since the lake is deeper and may have a rock bottom. But turbulence may easily churn the water so that gravel, sand and other debris are sucked into the irrigation system.
The sediment filter will catch most of this debris – and will need frequent cleaning. An additional factor is the Zebra Mussel. This organism can easily enter the irrigation system and grow in the pipes, valves and fittings. This invasion may render the irrigation system useless in one season.
For this reason, a Zebra Mussel filter should be used. These in-lake filters are expensive to install and need servicing 2-3 times a year. Their price is dependant on many factors including depth of water, bottom type and water flow needed. They filter out the larval stage of the mussel, preventing them from invading your irrigation system. Any other Zebra Mussel control is only cosmetic and will not offer the protection that a true Zebra Mussel filter provides.
Initial installation expenses are high for both the zebra mussel filter and the pumping system. Lake water is not free – there are installation costs, service costs associated over time as well as the constant monitoring of the filter and intake in the lake to ensure a constant clean water supply.