Washing machine use on septic system

I have a vacation home that was built in 1980 on a wooded lakeside lot. It has a well and a conventional gravity septic system. The septic tank is 1000 gallons. There is a toilet-sink-tub/shower full bath and a toilet-sink half bath. The house has 3 bedrooms and could sleep 7 to 10 people but we have never had more than 4 adults and 3 children at one time--even then the larger number only 2 to 4 days a year. The house is used from June to September and shut down in the winter. Our personal use is an extended 4-day weekend every week during the summer months.

For about 30 years we imited our use of an old Kenmore top loader washing machine (bought used) to once every 7 days or so. It probably dumped about 30 gallons per load. A couple of years ago it finally gave up the ghost and it was replaced with a basic Amana high efficiency top loader with auto-sensing water level. It probably uses less than 10 gallons for a typical load.

We have always used low/no-phosphate cleaning agents like Arm & Hammer and OXY Clean.

We are very conscientious about the possible effects on the water quality in the lake from runoff, etc. The lake is tested every year and the levels have stayed about the same. Our leaching field is as far from the lake as it can be and still be on our property (about 150 feet) and there are many mature trees and uncleared undergrowth between it and the lake.

The tank has been pumped several times for normal maintenance and the condition of it and the septic operation (crust, sludge, etc.) were reported as very good.

However I was just wondering whether what would have less impact on the septic system:

1. Running a load of laundry at the beginning of a 4 day stay each week when the system has had 3 days to digest, or

2. Running a load of laundry at the end of a 4 day stay each week with the possibility of over diluting the previous 4 days of usage?

And given our usage and 30+ year experience whether it even makes any difference?

Thanks for your input.

 

Option 3 check local code to see if you can "water" your yard with it. http://oasisdesign.net/greywater/laundry/

 

Note that, except for a week or so after after pumping the septic tank, the septic tank rests and remains at about 85% full. Then for each additional gallon of incoming waste water, a gallon of mostly treated water will exit for the leach field.

The dilution of the washing machine water by the rest of the septic tank contents would be the same whenever that new waste water is introduced.

With this in mind I think that there will be no difference between your alternatives 1 and 2.

Pumping a septic tank more often than needed has no additional benefts. Suggested starting point is after every two years worth of occupancy, lengthening that time inteval if the technician thinks not enough sludge and grease has accumulated.

 

I agree that there is no difference when you do laundry. A few loads of laundry is not much liquid compared to showers and washing dishes for seven people. The good news is that it sounds like you are doing everything right which will give your septic system 95% protection.

You mention trees and brush. Is any of that growing within 30 feet of your leach field?

 

Interesting info, Ray. I considered a separate drywell when I first installed the washer but there is no "yard" as such. All woodlands and very little of that on the road side of the house away from the lake. Dumping in or on the ground on the lake side would be counter productive and too near the well. (The lot is only 14,000 square feet.) As long as the volume does not overpower the septic system that is probably my best solution.

 

There are trees on two sides up to the edges of the field. Septic tank, walkway and house on one side and a single tree and parking space on the other. Very low undergrowth on the field itself. Hopefully nothing with a root system that will clog the pipes or invade the tank--at least not yet.

 

NO, septic is black water, if gray water (everything but toilets) is separate that could be used!

 

Have you ever added EcoSave or BioClean or other enzymes to your tank via a sink or toilet ?

 

The question is about washing machine discharge only.

Not that I recall, but why? Septic system is working fine according to inspections when pumped out. I think I looked into the need for enzymes once and found no compelling reason to use.

 

From the independent research I've read septic tank biologics don't do much. If you believe the manufacturers claims they are a wonder additive.

 

That was my conclusion, too.