Yes...no metal is suitable for sewage holding...
...because urine so corrosive that it makes salt benign by comparison. An aluminum tank will typically start to leak at a seam or a fitting within 2-5 years...and--as quite a few people here will attest--will turn the tank itself into collander in not much more time than that. The ONLY material we recommend for sewage holding is polyethylene, with a minimum wall thickness, even on the smallest tanks, of 3/8"...increasing in thickness for larger tanks. Thin walls can permeate, and cannot support the 8.33 lbs/gal that sewage weighs...they bulge, which stretches the thin plastic even thinner. A cheap thin plastic tank won't outlast aluminum by very long...a top quality thick-walled tank will last 20+ years.
