I am unable to agree with division II or the result. The court’s evaluation of the evidence departs from the principle that debatable questions as to reasonableness of an enactment are not for the courts but for the legislative body. See Goldblatt v. Town of Hempstead, 390 U.S. 590, 595, 82 S.Ct. 987, 990, 8 L.Ed.2d 130, 134 (1962); Adams v. Bonacci, 287 N.W.2d 154 (Iowa 1980); Incorporated Town of Carter Lake v. Anderson Excavating and Wrecking Co., 241 N.W.2d 896, 901 (Iowa 1976). Furthermore, the court’s view of the law cannot be reconciled with the recent reiteration and application of relevant principles in Woodbury County Soil Conservation District v. Ortner, 279 N.W.2d 276, 277-79 (Iowa 1979).
I. The evidence. Even though the validity of a police power enactment depends on its reasonableness, the constitutional inquiry is not answered by the court’s determination of what is reasonable. See Goldblatt, 390 U.S. at 595, 82 S.Ct. at 990, 8 L.Ed.2d at 134 (“this Court has often said that ‘debatable questions as to reasonableness are not for the courts but for the Legislature . . ’ ”); Adams, 287 N.W.2d at 154 (“Unless a law has no rational relationship to its intended purpose, we *521must defer to the legislature as to its wisdom. A challenging party must negate every reasonable basis upon which the act can be upheld.”); Carter Lake, 241 N.W.2d at 901 (“If [an ordinance] tends to accomplish a proper municipal object in a way which can find justification in the minds of reasonable people, it is reasonable. It is not unreasonable simply because a better means of accomplishing the same object might be conceived, nor is it unreasonable because it restricts the free use and enjoyment of property.”). Thus, the court’s task in the present case is to determine whether plaintiffs and intervenors met their burden to negate every rational basis for the conclusion of the board of health that the 1968 regulation was necessary to protect the public health. Examined in this light, the record shows they did not meet their burden.
The only persons who testified against the 1968 regulation at trial were plaintiffs Donald L. Kasparek and Rose Marie Kaspa-rek. Donald said only seven of the twenty-three lots in his 1966 subdivision and only seven of the forty-two lots in his 1968 subdivision were unsold at the time of trial. A sale of two other lots in the second subdivision was being held up because of the purchasers’ inability to get a permit for a septic tank. Of the seven unsold lots in the second subdivision, plaintiffs had set aside four for other purposes and expected to sell another to an adjacent owner. Although they showed their gross expenses in developing the tracts, they did not show they would suffer anything other than a diminution of profit if the remaining lots remained unsold. Nor did they offer any proof to show the extent of that lessening of profit.
Their evidence revealed they had actual notice of the proposed health regulation before they obtained approval of their second subdivision in 1968. While their second plat was still awaiting board of supervisors approval, they knew the board of health had already rejected their objection to the regulation.
The regulation does not foreclose development of affected lots. It simply requires a central sewage disposal system to be used, but includes an exception authorizing permits for private septic tanks if lots are aggregated into five-acre parcels.
Plaintiffs and intervenors offered no evidence to show it was unreasonable for the board of health to conclude that private septic tanks on each lot of the affected subdivisions would pose a sufficient risk to public health to justify the regulation. They did not explain why a central sewage system such as provided for in chapter 358, The Code, could not rationally be prescribed.
Intervenors established by stipulation that they owned vacant lots at the time of trial in subdivisions which were platted before the effective date of the regulation but which were subject to it. United State Bank, which did not acquire its lots until 1969, showed it had listed them for sale without success. It was agreed that one intervenor had been denied a septic tank permit because his lot was less than five acres in size. Intervenors’ evidence proved only that the regulation was being applied to them as it was being applied to plaintiffs, with similar results.
The only evidence on the public health issue was that of the board. Its evidence was that even a properly functioning septic tank poses health risks because it does not actually dispose of sewage. It removes approximately fifteen percent of the sewage strength by settling out solids but disperses the remainder of the sewage into the surrounding earth. What happens to it after that is a function of evaporation rate and absorptive qualities of the soil. The board’s evidence was that the evaporation and absorptive deficiencies were so great in the area of the watershed that pollution from private systems would inevitably reach Lake Macbride. Board witnesses said the problem was compounded by the absence of effective dilution because of the zero flow rate of the lake. This combination of factors was uniquely present in the area affected by the 1968 regulation. The board concluded the only effective remedy was a central system which would take the sew*522age elsewhere. However, the five-acre exception was added to the regulation as an expedient because the risk of pollution would be less if the number of households using septic tanks could be reduced.
Much of the board’s evidence came from testimony of Richard Shive, a civil engineer, who performed percolation tests in the watershed in 1964. He said he did so because he had “become aware of several sewage installations that had been made on the northerly portion of the lake which had failed and were discharging sewage on top of the ground, and which then ran into Lake Macbride and into the Coralville Reservoir.” Through his tests he demonstrated to the satisfaction of county officials that the engineer who made similar tests for the developers and individual lot owners, including plaintiffs, was producing inaccurate results. As a consequence, that engineer was barred from further testing. Shive testified that “on the basis of many percolation tests in the general area of the north arm and the failed systems, I concluded that the information was representative of the area and therefore the value of the property was marginal ... at that time, because a [septic tank] system couldn’t be built by then existing state standards.” He said two lots he tested in the Kasparek subdivisions were valueless in the absence of a central sewage disposal system because their percolation rate exceeded state standards. He believed a septic tank on one of the lots, although functioning properly, was actually polluting Lake Macbride at that time.
Shive became a member and chairman of the board of health after the Local Health Act, chapter 137, The Code, was enacted in 1967. See 1967 Session, 62d G.A., ch. 163. He served on the board for six years. He explained the background and purpose of the 1968 regulation in light of his experience before and during that tenure.
Another former board member also testified. He was Franklin J. Kilpatrick, director of the environmental health service and associate professor in preventive medicine and environmental health in the College of Medicine at the University of Iowa. He said the board was motivated to enact the regulation by multiple risks to health existing in the Lake Macbride area because of the inability of evaporation and absorption to dissipate the strength of sewage, which would reach the lake, where it would not be effectively diluted. He said he believed the only satisfactory system to safeguard the public health is a central sewage disposal system. The board told Donald Kasparek this in July 1968. Kilpatrick testified that a central disposal system would actually be less expensive than private systems and is the only adequate answer to the health risk from septic tanks.
When the board was urged by plaintiffs, intervenors and others to relax the regulation on claims of hardship, the board obtained studies and recommendations which led it to reject proposals for change.
This record shows the board conscientiously and carefully weighed the public health interest against the individual economic interests of plaintiffs and intervenors and came down on the side of the regulation. In view of this record, I am unable to agree with the court’s conclusion that the reasonableness of the regulation is not fairly debatable. I do not believe plaintiffs and intervenors showed the board acted irrationally in adopting it and making it applicable to existing subdivisions.
II. The law. Plaintiffs and intervenors rely on the due process and takings clauses of the United States and Iowa Constitutions. See U.S.Const. amends. V, XIV; Iowa Const. art. I, §§ 9, 18. These same provisions were involved in Woodbury County Soil Conservation District v. Ortner. See 279 N.W.2d at 277-78. We stated and applied the following principles of constitutional adjudication in that case:
1. “In considering the constitutionality of legislative enactments, we accord them every presumption of validity and find them unconstitutional only upon a showing that they clearly infringe on constitutional rights and only if every reasonable basis for support is negated.” Id. at 277.
*5232. When a taking occurs, compensation must be given; when police power is exercised to control and regulate property for the public good, no compensation need be paid. The point at which police power regulation becomes so oppressive it amounts to a taking depends on the circumstances of each case. The test is whether the collective benefits to the public outweigh the specific restraints on the individual. Factors of importance include the economic impact of the regulation on the individual and, particularly, “ ‘the extent to which the regulation has interfered with distinct investment backed expectations.’ ” The character of the government action is also important. Id. at 278 (quoting with approval from Penn Central Transportation Co. v. New York City, 438 U.S. 104, 124, 98 S.Ct. 2646, 2659, 57 L.Ed.2d 631, 648 (1978)).
3. An exercise of the police power is not invalid merely because it imposes an extra financial burden on individuals. “A law does not become unconstitutional because it works a hardship. . . The argument that one must make substantial expenditures to comply with regulatory statutes does not raise constitutional barriers.” Id. at 279.
The landowners in Ortner challenged section 467A.44, The Code 1975, which was the basis for conservation district orders requiring them to implement certain soil erosion control practices on their farms within six months. Even with a state subsidy, the landowners’ expense would be $12,000 in one case and $1,500 in the other. In addition, there were claims the process would remove substantial acreage from production, require additional equipment, reduce farm income, decrease the value of the land and bypass reasonable alternatives. Applying the relevant principles, this court unanimously held that the landowners did not meet their heavy burden to prove the statute violated the constitutions in the respects claimed. Id. at 279.
I believe a similar holding is compelled in the present case. The risk to public health apprehended by the board of health from pollution caused by septic tanks is more immediate and serious than the risk of soil loss in Ortner. The objective of the board was plainly reasonable. Moreover, the evidence was sufficient for a reasonable member of the board to conclude that the installation of a central sewage disposal system was an appropriate solution to the health risk and that the expedient of a five-acre limitation on the installation of septic tanks was the only tolerable exception. The question is not what this court in a de novo review of the evidence would say is an appropriate regulation; it is whether a rational board of health could reach the conclusion which the board did in this case. See Carter Lake, 241 N.W.2d at 901. The regulation is preventive. The fact that constant monitoring by percolation tests or nuisance actions after pollution occurs may be alternatives does not establish the irrationality of the means chosen by the board. See id. Exercise of the police power is not limited to remedial measures.
Principles in zoning cases relied on by the court do not show that the regulation amounts to a taking. In each of those cases the “vested right” was an “investment backed expectation” which would be totally and inevitably destroyed by the enactment. See, e. g., Keller v. City of Council Bluffs, 246 Iowa 202, 212-13, 66 N.W.2d 113, 119 (1954) (“The theory of vested rights relates only to such rights as an owner of property may possess not to have his property rezoned after he has a building permit and has started his construction or improvement. The rationale of such cases is that he has incurred obligations or liabilities for the work which he could not escape, and of these costs he would be deprived by such a rezoning.”). Thus, in Carter Lake the denial of a landfill permit would have deprived the owner of the right to operate a landfill the town had previously authorized. Similar total and inevitable losses were involved in Stoner McCray System v. City of Des Moines, 247 Iowa 1313, 78 N.W.2d 843 (1956), and Board of Supervisors v. Paaske, 250 Iowa 1293, 98 N.W.2d 827 (1959). As in Penn Central, Goldblatt and Ortner, the proof of alleged oppressiveness does not measure up to this standard in the present *524case. Furthermore, it is difficult to see how plaintiffs could make a “vested rights” claim as to their second subdivision when they knew the board of health’s position before they obtained approval of their second plat. See Huff v. City of Des Moines, 244 Iowa 89, 56 N.W.2d 54 (1952).
Even when proved, a reduction in value of property is not necessarily a taking. See Pennsylvania Coal Co. v. Mahon, 260 U.S. 393, 413, 43 S.Ct. 158, 159, 67 L.Ed. 322, 325 (1922) (“Government could hardly go on if to some extent values incident to property could not be diminished without paying for every such change in the general law.”); Ortner, 279 N.W.2d at 277-79. This is well illustrated by Carter Lake. A permit requirement that would destroy the right to operate a landfill which the town had granted by lease was invalidated as a taking. However, stringent new regulations on the manner of operating the existing landfill were upheld.
The United States Supreme Court has upheld exercises of police power which allegedly resulted in substantially reduced property values. See Village of Euclid v. Ambler Realty Co., 272 U.S. 365, 47 S.Ct. 114, 71 L.Ed. 303 (1926) (75 percent); Hadacheck v. Sebastian, 239 U.S. 394, 36 S.Ct. 143, 60 L.Ed. 348 (1915) (87½ percent). In Ortner we followed the analogous holding in Penn Central Transportation Co. v. New York City, 438 U.S. 104, 98 S.Ct. 2646, 57 L.Ed.2d 631 (1978).
Only five months after Goldblatt was decided, the Supreme Court had before it an appeal from a decision upholding a zoning ordinance which the trial court and California Supreme Court had agreed completely destroyed the economic value of the appellant’s land. The takings issue was squarely presented, but the Court dismissed the appeal for want of a substantial federal question. See Consolidated Rock Products Co. v. Los Angeles, 57 Cal.2d 515, 370 P.2d 342, 20 Cal.Rptr. 638, appeal dismissed for want of substantial federal question, 371 U.S. 36, 83 S.Ct. 145, 9 L.Ed.2d 112 (1962); Sax, Takings and the Police Power, 74 Yale L.J. 36, 43-44 (1964). We have recognized that such dismissals are on the merits and thus binding on us. See Beitz v. Horak, 271 N.W.2d 755, 758 (Iowa 1978). Under this authority, even if the regulation in the present case did deprive plaintiffs and intervenors of profitable use of their lots, the federal constitutional standard was not breached.
The relevant principles have recently been reaffirmed in Andrus v. Allard, — U.S. —, —, 100 S.Ct. 318, 326-27, 62 L.Ed.2d 210, 222-24 (1979). The analysis in Allard is apposite to the present case. It involved a takings challenge to an Interior Department regulation which the Court found had the effect of barring the sale of eagle parts which had been obtained prior to the effective date of the authorizing statute. The Court reiterated the principles which had been announced in prior cases, pointing out: “[G]overnment regulation— by definition — involves the adjustment of rights for the public good. Often this adjustment curtails some potential economic use or economic exploitation of private property. To require compensation in all such circumstances would effectively compel the government to regulate by purchase.” Id. at —, 100 S.Ct. at 326, 62 L.Ed.2d at 222. After noting that the regulations did not require the surrender of the artifacts or involve a physical invasion or restraint upon them, and despite what the Court called the “undeniable” fact that the regulations prevented the owners from making the most profitable use of their property, the Court held that the prohibition against sale did not effect a taking. Id. at —, 100 S.Ct. at 327-28, 62 L.Ed.2d at 223-24. The present case comes well within the Allard principles.
I would hold that plaintiffs and interve-nors failed' to meet their burden to show that the 1968 regulation denies them due process or constitutes a taking.
REES, UHLENHOPP, and HARRIS, JJ., join this dissent.